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84 blazer rearend in 50 GMC?
#346798 Mon Dec 10 2007 01:37 AM
Joined: May 2001
Posts: 12
M
Mildman Offline OP
New Guy
Well I've bought, sold, hoarse traded and most important learned lots just reading posts. Now it's time to ask a Question. I just bought a 283 & turbo 350.now it's time to decide on rearend. The same guy that sold me the engine and tranny has an 84 blazer rear.Is this an easy fit? Did a search and only ref to blazer rear was for 46 chev. also saw where 66 rear was good fit. Any responses would really help.







Re: 84 blazer rearend in 50 GMC?
Mildman #346844 Mon Dec 10 2007 03:22 AM
Joined: Oct 2006
Posts: 5,029
B
Master Gabster
What's the width of the Blazer rear? I assume the GMC is the same as the Chevy. You probably need something 62/64" from flange to Flange.


Jim

Modern ‘science’: the wonder of a
pre-determined mind…

The ‘baseline belief’ of astronomy:
“Any day now, we’ll pick up a tiny,
coded signal from outer space. Then
we’ll know for certain that there is
intelligence out there, because coded
information does not arise by chance”

The ‘baseline belief’ of biology:
The precisely coded genetic information in
every cell would fill many books…
but we know for certain that no intelligence
could have created life.”


Re: 84 blazer rearend in 50 GMC?
Mildman #347337 Tue Dec 11 2007 03:42 AM
Joined: Nov 2007
Posts: 20
M
mbt Offline
Apprentice
Might look at a late 80's Camaro also.

Re: 84 blazer rearend in 50 GMC?
mbt #347375 Tue Dec 11 2007 05:53 AM
Joined: Oct 2006
Posts: 5,029
B
Master Gabster
I have an 80 Camaro 10 bolt on mine. I looked for a Ford 9" which is really a great rear if you will be racing with mucho horses. If not I would stick with the Camaro rear end. However remember to look before you leap. Always check the search feature here for more information on any subject that cost $$$$$.
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" rear-end 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 rear ends, such as the Dana 44, and some weird Australian rear-end. Of course, if you want to make sure, get out your tape measure and check yourself! I may be wrong.
There are lots of rear ends available! Some fit better than others. For 6 lug rear ends, 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 Advanced Design or Task Force truck as long as you don't get too wild with wheel/tire width. The heavy duty models have a 2.75 brake shoe, thats stopping power. The 12 bolt truck rear ends 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 rear ends 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 rear ends, and leaf springs. These rear ends 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 rear-end was available as an option in 59 Chevy trucks, equipped with positraction...rare, and with a 3.92 ratio. I have one of these rear ends; 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 rear-end is not too popular a swap, unless you get the 70-up 4wd 6 lug axles. Chevy also used 10 or 12 bolt rear ends in lots of cars, in varying widths. The heavy duty models have a 2.75 brake shoe. A common one is the 61" wide 70s vintage Camaro/Chevelle/Nova (and clones) 8.5" rear-end. 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 rear-end 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 rear-end! The 55-57 Chevy car rear-end 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 rear-end 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 rear-end, with all the mounting brackets that need to be cut off. The Ford 8" and 9" rear ends come in a whole bunch of varieties, and only a few are useful in old trucks. 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 mid size cars, such as the Fairlane, have a rear-end 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 rear ends 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" rear-end, 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 rear-end 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 lots of weight, and you don't have much engine...just don't plan on going much faster than 55!

Last edited by BIG CHEVY 3600; Tue Dec 11 2007 05:57 AM.

Jim

Modern ‘science’: the wonder of a
pre-determined mind…

The ‘baseline belief’ of astronomy:
“Any day now, we’ll pick up a tiny,
coded signal from outer space. Then
we’ll know for certain that there is
intelligence out there, because coded
information does not arise by chance”

The ‘baseline belief’ of biology:
The precisely coded genetic information in
every cell would fill many books…
but we know for certain that no intelligence
could have created life.”


Re: 84 blazer rearend in 50 GMC?
BIG CHEVY 3600 #348436 Thu Dec 13 2007 11:32 PM
Joined: May 2001
Posts: 12
M
Mildman Offline OP
New Guy
Big Chevy 3600, thanks for all the info sure gave me alot to think about and research. Merry Xmas to all that read this

Re: 84 blazer rearend in 50 GMC?
Mildman #349701 Mon Dec 17 2007 05:49 AM
Joined: Nov 2007
Posts: 20
M
mbt Offline
Apprentice
I have an '89 Camaro rear end and it measures out great. If you can find a disc rear end that would be sweet.

Re: 84 blazer rearend in 50 GMC?
mbt #349713 Mon Dec 17 2007 07:08 AM
Joined: Jul 2005
Posts: 2,046
C
Shop Shark
http://s67.photobucket.com/albums/h298/1951otter/?action=view&current=Scan1_0001-1.jpg
see
http://www.stovebolt.com/ubbthreads/ubbthreads.php/ubb/showflat/Main/8785/Number/55993#Post55993
&
http://www.stovebolt.com/ubbthreads/ubbthreads.php/ubb/showflat/Main/9025/Number/57576#Post57576
&
http://www.chevytrucks.org/tech/rear_ends.htm
&
http://www.stovebolt.com/ubbthreads/ubbthreads.php/ubb/showflat/Main/7628/Number/47910#Post47910
&
I used a 1977 4x4 suburban heavy duty 12 bolt- 3.40:1 ratio and a T5 hybrid. just about any 10 or 12 bolt should fit. do you want 5 or 6 lug wheels? and ratio.


Want to know about swapping out a rear end.
and what to use Here's food for thought.... on 50s chevys 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 a Advanced 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!
&







Last edited by carolines truck; Mon Dec 17 2007 07:48 AM.

Jim & Caroline

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Better use your good sense."
Gooday
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Re: 84 blazer rearend in 50 GMC?
carolines truck #349829 Mon Dec 17 2007 07:15 PM
Joined: Oct 2006
Posts: 5,029
B
Master Gabster
Hope this doesn't duplicate what has been said...
Also concerning the disc brakes, 2002 Firebird disc will bolt right up to the 10 bolt Chevy axles.


Jim

Modern ‘science’: the wonder of a
pre-determined mind…

The ‘baseline belief’ of astronomy:
“Any day now, we’ll pick up a tiny,
coded signal from outer space. Then
we’ll know for certain that there is
intelligence out there, because coded
information does not arise by chance”

The ‘baseline belief’ of biology:
The precisely coded genetic information in
every cell would fill many books…
but we know for certain that no intelligence
could have created life.”


Re: 84 blazer rearend in 50 GMC?
BIG CHEVY 3600 #349843 Mon Dec 17 2007 07:56 PM
Joined: Dec 2003
Posts: 2,736
Shop Shark
GUYS...GUYS!, please try to keep your responses to a reasonable length. I don't know who is quoting who in these responses but someone is trying to hijack someones else's prior answer. Not good.


1953 Chevy 5-window 3100
In the Stovebolt Gallery
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Dave
Engine & Driveline Moderator

If you can't make seventy by an easy road, don't go. ~~ Mark Twain
Re: 84 blazer rearend in 50 GMC?
53moneypit #349892 Mon Dec 17 2007 10:34 PM
Joined: Oct 2006
Posts: 5,029
B
Master Gabster
Good point Dave!
The first lengthly diatribe was from me and I thought I had made it parenthetically as it was copied from another site with no credits as to whom it was from. When I saw my credit to that brilliant and much published character A. Nonymous was left out I tried to edit but my computer locked up and I left it as it was.


Jim

Modern ‘science’: the wonder of a
pre-determined mind…

The ‘baseline belief’ of astronomy:
“Any day now, we’ll pick up a tiny,
coded signal from outer space. Then
we’ll know for certain that there is
intelligence out there, because coded
information does not arise by chance”

The ‘baseline belief’ of biology:
The precisely coded genetic information in
every cell would fill many books…
but we know for certain that no intelligence
could have created life.”



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