The Stovebolt Site Forums The Shop Area Engine Shop Understanding rear ends

Hi All,
A week or so ago I asked for advice on ifs for my truck, now I need rear end help. I am looking for a 3/4 ton rear with a 3 something ratio. I found a 77 rear end and was told that it was a trailing arm rear end. What does that mean? What years am I looking for if I am looking for a 1/2, 3/4 ton rear? At this point I don't care about bolt pattern, I am just after what years are suitable. I did a search and most of the information does not include modern truck rear ends, lots of cars are suggested but not truck. Can someone help this lost soul?
Thanks, Rick

How heavy of a rear are you needing? If you don't think that you need a full floater, you might consider the 14 bolt 9 1/2" ring gear from an '88 and up light 3/4 ton. Many of them have 3.42 or 3.73 gears and they can be had fairly cheaply. Most also have the 6 on 5 1/2" bolt pattern for the wheels. Stay away from the 4x4 version, it's too wide. On that '77 rear, it should be a leaf spring unit, the last trailing arm rear was '72.

Rick in VA,

For GM rear ends for your 51, take a look at 67-81 Camaro/Firebird/Nova rear ends. The width is about right.

Another modern rear I have looked into is a rear end out of a Trail Blazer. Since they came out in 2002, there are many around. The width again is about right. I am finding a Trail Blazer rear end easier to locate than one out of a 70's vintage GM.

Price for the trail blazer around here is $350 at the bone yard.

S-10 4X4 rear end will also fit your truck. Stay away from the 4X2 S-10 rear....too narrow.

No mistery to gearing the lower the first number the more top end you'll get. The higher the first # the more low end pulling power you have. When they write ratios they leave off the last part of the ratio. That is to say a 4.11 actualy reads 4.11/1. The 2 numbers together are the ratio. Unfortunatly, they make these numbers (gear ratios) to hard to calculate in you head.
To make it more simple to understand in your head, if some one tells you it is a 3.42 round it up or down to the closest whole number. A 3.42 would be a 3 and then put a / and a 1 behind it.
3/1 it means it takes 3 revolutions of the drive shaft for 1 revolution of the wheel. A 3.73 would round to 4/1. So it would take 4 revolutions of the drive shaft to turn the wheel 1 revolution. This is for explanation purpose only. If you do it my way a 3.73 and a 4.11 would be the same thing (4/1) There is a noticable differance between the 2 ratios in reality. Do you see what I am talking about? Or did I just add to the confusion.

I have a Dana 60 from a 3/4 ton ford van with 3.54 gears. It is an 8 lug semi floating with 1.5" 35 spline axles (the largest available for the Dana 60). I was told it was about the right with, but have not measured it.
If you are interested I'll go take a look?

I'll have to keep an eye on this thread.
I know that I want about a 3.55 and the width to be perfect (60 inches I believe?).
I keep hearing that the Nova is popular for this...

HI!
I really wanted to get a truck rear end. I wish I could say that my truck would never have to pull its own weight, but it will be put to use. I have avoided the Pinto front end for this reason. I want to put 3/4 ton of wood in it and drive down a rutted gravel road. I do not believe a Camaro rear end would be the best choice for this. That is why I am looking for a 3/4 ton truck rear. Any thoughts on a truck rear? Rick

I just measured the Dana 60 rear that I have available. It measures 66.875" from wheel mounting surface to wheel mounting surface.
The original rear from my 52 1 ton measures 62.875".

So, with wheels with about 2" more backspacing than original the ford van axle will work. Or, with a flat bed original wheels would work.

The Trailblazer rear has an odd bolt pattern, it's not the standard 6 on 5 1/2". I think it's 6 on 4 3/4". You would have difficulty in matching wheels for that one as currently all the wheels for it are a high offset design that would rub in the fenderwells.
A Dana 60 from a Dodge van would fit in a 3/4-1 ton AD with no wheel problems, I know of a truck that is set up with one of these. I would think that a rear from a 1 ton G series van would fit as well. You might be able to use the front suspension crossmember as well.

Hi Grigg,
What do you want for the Dana 60 rear?
Rick

Hey Rick,
Since no one has asked, is there a rear end in your truck now?
If so, why not just leave it in and change the 3rd member, you have lots of choices and there are lock out kits for those rear ends as well.

Ray

Hi Truckasaurus!
Yes, there is the 3600 rear end in it now. It has the standard very low gears. No one makes a ring and pinion for this differential, 3100, yes, 3600 no. So the only way to get a better ratio is to go to another differential. I know I can change 3rd member but the best you can do with that is 4:11. Some say there is a 3:90 pumpkin that will fit but I have never found one. And if I were to find one it would be an Eaton rear that no one keeps parts for anymore.
That is why I am searching for a more modern differential, one that I can get better gears for. Any suggestions?
Rick

I used a 1977 3/4ton suburban 4x4 chevy 6 lug heavy duty 12 bolt rear end for my 51 3104. The brake shoes are 2-3/4''. It fits great w/ plenty of stopping power. the e~brake is the correct outer length and the inner cable can be made to fit. they come in three 'usual' ratios and if you by the wrong one they can easily be changed to what you want.

what tranny do you run?????
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Want to know about swapping out a rear end.
and what to use Here's food for thought.... on 50’s chevy’s By: Jim Forbes

The 82-newer Camaros are wider than the older ones, so you should stick with the 70-81 models. The 75-79 Nova uses the same rear as these older Camaros, I believe. The 68-74 Nova chassis is the same as a 67-69 Camaro; the 75-79 Nova chassis is the same as the 70-81 Camaro. The 82-newer Camaros used the small 7.5" rearend design that the 78-newer Malibu/Monte Carlo/regal/cutlass etc used, but it's quite a bit wider. Some of the 82-newer Camaros used different rearends, such as the Dana 44, and some wierd Australian rearend. Of course, if you want to make sure, get out your tape measure and check yourself! I may be wrong.
Here's another one from Jim on the subject---- There are lots of rearends available! Some fit better than others. For 6 lug rearends, the 64-69 1/2 ton 2wd Chevy (and some GMC) trucks have a 12 bolt rear, about 60-61" wide (I measure them where the wheels bolt on).
The 70 2wd and 70-81 4wd have a 6 lug 12 bolt that is a couple inches wider, but will fit under an advance design & Task Force truck as long as you don't get too wild with wheel/tire width. The 12 bolt truck rearends from the 60s usually had 3.70 gears, which is a bit much for extended highway driving at 75 mph. You can swap the differential carrier and ring/pinion gears from a later TRUCK or VAN 12 bolt, the 70s trucks usually had 3.08 or 3.40 gears. Of course, you'll need to know how to set up ring/pinion gears, bearing preload, and all that other neat stuff to do this.
These 60s truck 12 bolt rearends are from coil spring trucks, so the perches are in the wrong place, and they have some extra stuff on the housing for a panhard bar, which you won't need with leaf springs. Most 60s GMC trucks, and some Chevys, had Dana 44 or Dana 60 rearends, and leaf springs. These rearends are 6 lug, about 60" wide, and will bolt into a Task Force truck (with some fudging, the perches are about 1/2" too far apart). The brakes use different parking brake cables, which is a problem, and the drums have a different offset. Gear ratios range from 3.21 to 3.92 normally, the 3.21 is found behind some GMC V-6 engines, and is a nice ratio for an old truck. The Dana 44 uses a standard Chevy 1310 yoke, but the Dana 60 uses a heavy duty yoke, which takes a larger 1350 series ujoint. A similar Dana 40 rearend was availalbe as an option in 59 Chevy trucks, equipped with positraction...rare, and with a 3.92 ratio. I have one of these rearends, it was in my extended cab truck...I'm saving it for when I build a race truck (one of these years).
The 71 and newer 2wd trucks use a 5 lug 5" bolt pattern, same as the 71-76 full size cars. There is not much available in the way of matching front brake rotors that will fit an old truck, so this rearend is not too popular a swap, unless you get the 70-up 4wd 6 lug axles. Chevy also used 10 bolt rearends in lots of cars, in varying widths. A common one is the 61" wide 70s vintage Camaro/Chevelle/Nova (and clones) 8.5" rearend. In Camaros/Novas it has leaf springs, but the perches won't work with old truck springs. In Chevelles, it has coil springs, with lots of extra brackets to cut off, and the cast in mounting "eyes" on top, where the upper control arm bushings fit. Wheel bolt pattern is 4.75", and there are front disk brake kits available to match, or you can use the 53-54 car front hubs/drums on the original 50s truck brakes, to get the same bolt pattern front/rear. This is a good rearend for using in an old truck, the ratios are commonly 2.73-3.36, with higher gears available. The axle shafts are usually worn out in these things, so check them (pull the cover, lockpin, and C clips out to get them loose) where they ride in the wheel bearings...before buying the rearend! The 55-57 Chevy car rearend is almost a bolt in, the perches need to be relocated to the top of the housing though. It has the 4.75" bolt pattern, and ratios are usually 3.55-3.73, but sometimes you'll find a 3.36. The 78-88 mid size GM cars use a 7.5" 10 bolt, which is about 58/5" wide. This rearend would work well in an early (older than 47) truck, but it is quite light duty. Ratios are usually 2.29-3.23, which means you want some torque in the engine to pull it...but rpm will be low. This is a coil spring rearend, with all the mounting brackets that need to be cut off. The Ford 8" and 9" rearends come in a whole bunch of varieties, and only a few are usefull in oletrucks. The late 50s full size cars have a nice one, but it's not easy to find brake hardware, drum, etc anymore. The mid 60s midsize cars, such as the Fairlane, have a rearend that is about the right width, and would be a good candidate...if you can find one. The Maverick/Granada is very narrow, about 56.5", and would not fit anything but a very early truck, or perhaps a tubbed Pro Street truck. The 60s full size Ford car rearends are usually too wide, but if you find one, measure it and see! Most earlier full size, and all mid size, cars use the 4.5" bolt pattern, while later full size cars use the 5" pattern. The Ford trucks have a big 5 on 5.5" pattern, with a big center that takes some work to redrill to anything Chevy. Ratios range from 2.47 to 4.30, and the axles come in 28 or 31 spline varieties. There is lots of interchange possible with the 9" rearend, which is why it's so popular...I have one in my 55 Belair, and in my 57 Suburban chassis. Unfortunately, they are getting expensive, especially when you have to shop around for just the right one that will fit. So...if you don't know if a rearend will fit, or what it came from, get out your tape measure and see for yourself! The most important things are overall width, and wheel bolt pattern...then concern yourself with ratio. I like a 2.75-3.0 ratio for a V-8 powered truck that will spend lots of time on the highway; about 3.2-3.7 for a 6 cylinder or small V-8 for in town and limited highway use, and the stock 3.9-4.56 ratio is great if you have to use your truck to haul lotsa weight, and you don't have much engine...just don't plan on going much faster than 55!

http://www.chevytrucks.org/tech/

Suspension Measurements


REAR SUSPENSION:
The following is a general list of rear ends and their dimensions to help narrow the search for a possible candidate to replace the torque tube rear end or just get a better set of gears for highway driving.
Advance Design Trucks seem to be using rear ends with widths ranging from 58"- 62". I'm not sure of the Task Force width ranges at this time.
Contributing information were Bob Welch, J Forbes and various locations throughout the Web and Automotive Magazines.
Rear Axle Measurements
MEASURED ACROSS WHEEL MOUNTING SURFACE
56 1/2" 71-77 Ford Maverick 8",
57" 71-74 V-8 Mavericks 8", All '75-77 6's & 8's Maverick 5 Lug 8", 49-51 Ford, 57-59 Ford 9"
57 1/4" 64 1/2 - 65 Mustang
58" 78-88 Mid sized GM Car, Malibu/Monte Carlo (82 up Metric Studs), 80 Granada & Lincoln Versailles,
67-70 Mustang/Cougar/Fairlane, Regal with 10 bolt axle, S-10 P.U., 65-67 Nova
58 1/2 " Ford Grenada
59" 68-83 Corvette
60" 55-64 Chevy Car, 67-69 Camaro, 64-67 Chevelle, 68-74 Nova, 71-73 Mustang/Cougar, 84-95 Corvette
60-61" 64-69 1/2 ton 2wd Chevy/ Some GMC 6 lug rear end 12 bolt Coil spring set up Possible gear ratio's 3.70
62" 64-77 Chevelle, 73-76 Torino, 89 Trans Am,
70 2wd 6 lug rear end 12 bolt Possible gear ratio's 3:08, 3:40, 3:73
70-81 4wd 6 lug reared ...............................................................
71- Newer 2wd trucks use a 5 on 5 lug pattern
71-76 Full Size Cars " "" "" "
60" 60's GMC and some Chevy's Dana 44 or Dana 60 with leaf springs 6 lug, Gear ratio's 3.21 to 3.92. GMC V-6 used a 3.21 Dana 44 used a standard chevy 1310 yoke, Dana 60 used the heavy duty yoke which takes the larger 1350 yoke.


Approximate rear end widths measured from backing plate to backing plate.
Add Width to compensate for drums as follows:
4" - 5" for small cars 5" - 6" for intermediate cars 6" - 8" for large cars
48" - 49" 50" - 51" 52" - 53"
'71 Colt
'72 Cricket
'72-75 Datsun Pickup
'72-73 Mazda '65 Ram American
'74 Valiant '28-40 Ford , '57 - 59 Ford
'62 Buick Skylark, '67 Chevrolet Six
'67 Mustang Six , '68 AMX
'69 Javelin Six , '70 dodge
'70 Duster , '71-77 Maverick
'71 Comet , '71- 72 Pinto
54" -55" 56" -57" 58" - 59"
'39 -48 Chevrolet, '68 GTO
'41 -48 Ford, '68-72 Chevelle
'55 -57 Chevrolet, 68-69 Fair lane 6 or 8
'66 Falcon, '69 Chevrolet
'67 Mustang V-8, '69 Firebird
'69 Cougar, '71 -73 Nova
'73 Ventura, '73 Mustang '36 Plymouth, '54-56 Ford Pickup
'67 Lincoln, '69 Dodge
'69 Dodge Van, '71 Torino
'72 Cougar, '74 Pontiac '49 Plymouth, '61 Chevrolet Impala
'65 Cadillac, '66 Buick Wildcat
'66-67 Chevrolet Big Car, '72 Charger
'69 Oldsmobile 88, '72 Chrysler
'72-73 Torino


STOCK CENTER TO CENTER SPRING PERCH DISTANCE
25" 39" 42" 42 1/2
'68 - 72 Chevelle '71 Colt
'73 Mazda '68 -71 Fairlane/Torino
'49-51 Ford '69 Chevrolet
'69 Nova
'71 - 72 Pinto
'73 Ventura
43" 43 1/2" 44" 46 1/4"
'65 Ram American
'64 1/2-'65 Mustang
'67 Mustang
'70's Ford Grenada
'69 Firebird
'70 Dodge '71-77 Maverick
'70 Duster
'70 Nova
'71 Comet
'72 Dart
'72 Cougar
'74 Valiant '57 Ford
'67 Chevrolet Six
'68 AMX
'69 Javelin Six '69 Dodge
47 1/2" 48" 51" 57 1/2"
'39 -48 Chevrolet
'67 Chevrolet big car
'72 Charger
'72 Chrysler '69 Dodge Van
'69 Ford Van '67 Lincoln

BACK TO TOP OF PAGE


The following list of extensive information was contributed by R. Welch:

Original Vehicles
Rear Suspension Width (Flange to Flange)
Year Classic Vehicles Width
26-39 Plymouth-Dodge car/pick up 56-58"
40-52 Plymouth-Dodge car 60-62"
26-39 Chrysler/DeSoto Car 60"
Most Early Mopar's 56-62"
25-39 Chevy Car 56-58"
26-46 Chevy Truck 56-58"
40-48 Chevy Car 58-60"
49-54 Chevy Car 58-60"
47-54 & 55 1st Series Chevy Truck 60-62"
Most Early Buick,Olds, Pontiac 58-61"
28-31 Ford Car/Pickup 57 1/2"
32 & 33-34 Ford Car/Pickup 56 1/2"
35-48 Ford Car 57-60"
35-41 Ford Pickup 56-60"
49-58 Ford Car 57-58"
49-56 Mercury 57-58"
49-51 Mercury 61"
64 Falcon 58"
67 Cougar 60"
55-59 Chevy Pickup 62"




Donor Vehicles Front and Rear
Suspension Width (Flange to Flange)
Year Classic Vehicles Width Front Width Rear
74-79 Ford Mustang II/Pinto & Mercury Capri/Bobcat 55 ½" 55 ½"
71-77 Ford Maverick with 8" axle 56 ½"
75-80 Ford Granada with 8" axle 57 ½"
64-66 Mustang 57"
67-71 Mustang 59"
72-73 Mustang 60"
67-69 , & 60" Camaro 60"
64-67 Chevelle 60"
55-64 Chevy car 60"
65-67 Nova 58"
68-72 Nova 60" 60"
78 & up Monte Carlo, Regal, etc. with 10 bolt axle 58" 58"
68-72 Chevelle with 10 bolt axle 61 ½"
89 Trans AM (Disc brake) 62"
76-80 Camaro/Firebird 61 ½" 60 ½"
68-83 Corvette 58 ½" 59 ½"
84-95 Corvette 59 ½" 60 ½"
Early 70's "A" body (Dart/Duster) with V8&3/4 axle 58"
"E" Body (Cuda) with V8&3/4 axle 58"
Dodge Dart 59" 55 ½"
Plymouth Volare & Dodge Aspen 61" 60 ½"
71 Blazer (6 lug) 63 ¾"
75-78 Granada 9" (43" perch to perch) 52 ¼"
75-78 Maverick 9" (43" perch to perch) 56 ¼"
81-87 Olds Cutlass 58 ½"





FRONT SUSPENSION INFORMATION

Track Width of Popular Donor Car Clips
Manufacture Model Years Track Front/Rear Curb Weight
Chevrolet Nova 68-74 59.8-59.6 3,770
Buick Apollo 68-74 59.1-58.8 3760
Pontiac GTO 68-74 59.9-59.6 3880
Chevrolet Corvette 68-83 58.7-59.5 3655
84-95 59.6-60.4 3890
Chevrolet Camaro (Z28) 76-80 61.3-60.5 3820
Pontiac Firebird (TA) 76-80 61.3-60.5 3900
Ford Mustang II 74-79 55.6-55.8 3305
Pinto 74-79 55.6-55.8 3305
Mercury Capri 74-79 55.6-55.8 3305
Bobcat 74-79 55.6-55.8 3305
Chevrolet Monte Carlo 78-86 58.5-58.8 3235
Buick Century 78-86 59.0-58.8 3700
Pontiac Grand Prix 78-86 58.9-59.0 3735
Plymouth Volare 75-79 61.0-60.5 3395
Dodge Aspen 75-79 61.0-60.5 3395
Dodge Dart 76 59.2-55.6 3600

Table taken from "How to Build a Custom Classic Truck" Peterson Publication; June or July 1999
Written by: Don Emmons & Mike Briggs

Great article...

Here's one I might have missed...

Early 90's chevy caprices are a dime a dozen down here. Does anyone have any tech info on these. I wonder if it would work.

Thanks,
Mario

Those Caprice Classics were often used as cop cars and then turned into taxi cabs. Both Police and Taxi companies do a good job servicing their vehicles. The Police versions of the caprice came with beefed up brakes and suspensions which included posi/limited-slip rear differentials. After scouting several in the junk yards I found most of the 10-bolt posis under those caprices were 62" from mounting surface to mounting surface, had 5 on 5" bolt pattern, 12 drum brakes, 3.42 gears and an oversized rear swaybar that would be perfect under these trucks. I was going with a slightly larger rim so needed a 64" wide differential with a 5 on 4 3/4" bolt pattern to match my front disc brake conversion.

NM51,
What rear end did you end up getting?
I was thinking of putting 9 or 10 inch wide wheels in back to go along with a mustang II up front (I hope).

The GM corporate 14 bolt full float rear axle is cheap and available in junk yards. There are not as many gear sets as are available for a Dana 60, but those are more expensive. Disk brake kits are available. Standard bolt patterns are available. Lockers are cheap.

If you want to haul anything with your truck, then this axle will handle more than your frame will. Most people consider this a bullet proof axle... it just weighs a lot.

Once this truck is done, it will be for pleasure only...no towing or anything like.
I just want to make sure I get the best rear end to fit my plans. I am still new to the game and learning tons from this site thankfully. There are so many options for this particular choice that I want to make sure I do the right thing...

I ended up using a 65" 12 bolt posi from a '69 chevelle ss with 3.73 gears- I went through it before installing it, replaced the bearings, seals, etc... and reset the preload.

It used to be that the 12 bolts were more desirable than the 10 bolts, but I believe that the quality and strength on the 10 bolts improved alot and they are just as strong as a 12 bolt, or stronger.

I've heard over and over again that the real weak link in the gm axels is the c-clip design. However, I've never seen an axel come apart due to c-clip failure. Nonetheless, you can't use c-clip axels in NASCAR without a c-clip eliminator kit.

The ford 9" is a very popular and common axel because it is easy to work on and everywhere. Next time I do one of these trucks I'll find a 9" with disc brakes and then if I don't like the gearing it's easier to change the gears with 9" than GM by far.