I’m gathering parts for my T5 5spd conversion and I want to make sure I buy the correct rear end / differential. My truck is a 1946 1/2 ton. I need an open differential and had read on the threads that any 1955.5 through mid 60’s Chevy truck will work well. Is this correct? What year model differential assembly should I be looking for? (Wanting to maintain 6 lug wheels).
Care taker of a 1946 1/2 ton. Pretty much period correct original. Danny T, from B’ham, Al
~ Dan 1951 Chevy 3 window 3100 Follow this story in the DITY Gallery "My Grandpa Carl's Truck and How it Became Mine" 1966 Chevelle (Wife's Hot Rod) | 2013 Chevy Silverado (Current daily driver) US Army MSG Retired (1977-1998) | Com Fac Maint Lead Tech Retired (1998-2021)
Thank you, Gdads51. That article still didn’t say what differentials are best to interchange. It just references swapping a 1955 thru 1958 pumpkin᠁..whic is very hard to find. Aren’t there other options? Can a 1955 thru 1967 differential not interchange?
Also, the shared article says I must change my spring perches if I do the 55-58 pumpkin swap. Why would I need to change my spring perch if I’m using My original stock differential housing, if I’m just swapping the pumpkin?
Care taker of a 1946 1/2 ton. Pretty much period correct original. Danny T, from B’ham, Al
Also, the shared article says I must change my spring perches if I do the 55-58 pumpkin swap. Why would I need to change my spring perch if I’m using My original stock differential housing, if I’m just swapping the pumpkin?
On your rear axle there are mounts that let the axle housing swivel up and down. The torque is resisted by –- wait for it –- the torque tube around your driveshaft. With an open driveshaft the springs resist the torque and need to be solidly attached to the axle tubes. The pivot mounts can’t do that.
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
... so the answer to DLTALFA's question is "you wouldn't need to change the spring perch if using the original rear axle housing".
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12 '52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
... so the answer to DLTALFA's question is "you wouldn't need to change the spring perch if using the original rear axle housing".
But he wants to change to an open driveshaft differential, which gets rid of the original torque tube.
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
Correct. There are so many different, and often contradicting, posts about which rear end assembly to use. I just want to make sure I buy the correct assembly first time, and not start a carousel of different purchases trying to get it right.
I’m keeping my original 216 engine, going with an early S-10 T5 5spd transmission᠁᠁and I need a correct “open drive differential” that will; (1)- fit correctly and (2)- install with the least amount of modifications, and (3)- work well with my engine / transmission configuration. (4)- while maintaining a 6 lug configuration so I can keep my artillery wheels.
Last edited by Dltalfa; 11/22/202210:31 AM. Reason: Correct error
Care taker of a 1946 1/2 ton. Pretty much period correct original. Danny T, from B’ham, Al
The axle I used in my '46 is from a '58. Deal of the century, $75 and it was completely rebuilt with Toms axles, side gears, bearings, 3:38 gears and new brakes.
The newer axles are wider than the original in your truck but there is plenty of room in the fenders so no worries there. The brakes will also be different, you have Huck drums now and the newer axle will have Bendix drums. It won't matter to your hydraulics, but the parking brake will have to be modified. I used cables to match the new axle and did some adjusting on the cable hangers and moved the keeper for the cable adjusters on the pull rod forward a few inches. My parking brake handle is mounted to the transmission adapter plate with a flat bracket that I made in the shop. The spring perches are easy to obtain as they are the same size as Jeep parts. If you get a driveshaft from an S10 you'll just need to have the length changed and you're off to the races.
Any time you are going to open drive you will have to deal with spring perches, e brakes, driveshaft etc. Check your gear ratios of both t-5 and rear you are hoping for as well as your original rear width. I think the width is very important to the goal of a good look. trucks got wider as they evolved and even some of the s10’s are too wide. I’ve heard the nova rear is the best width fit and usually already has a usable ratio.
Last edited by 37 GC; 11/24/20221:15 AM.
Larry Old man᠁Old truck᠁neither one goes very fast. All you need in life is TIME, PATIENCE and MONEY. If you are missing one component, you'll need an abundance of the others two.
The axle I used in my '46 is from a '58. Deal of the century, $75 and it was completely rebuilt with Toms axles, side gears, bearings, 3:38 gears and new brakes.
The newer axles are wider than the original in your truck but there is plenty of room in the fenders so no worries there. The brakes will also be different, you have Huck drums now and the newer axle will have Bendix drums. It won't matter to your hydraulics, but the parking brake will have to be modified. I used cables to match the new axle and did some adjusting on the cable hangers and moved the keeper for the cable adjusters on the pull rod forward a few inches. My parking brake handle is mounted to the transmission adapter plate with a flat bracket that I made in the shop. The spring perches are easy to obtain as they are the same size as Jeep parts. If you get a driveshaft from an S10 you'll just need to have the length changed and you're off to the races.
Steve
. Thanks! I’m trying to maintain my 6 lug Artillery Wheels, so I’ll stay with an early Chevy setup. Good to know about the S-10 drive shaft
Last edited by Dltalfa; 11/24/20225:38 PM.
Care taker of a 1946 1/2 ton. Pretty much period correct original. Danny T, from B’ham, Al
I use a 1979 Chevy Nova. The ratio is 2.73 and I run an s10 5-speed Has good acceleration and I cruise at 2000 rpm at highway speeds.
Don't know which ratio your tranny has in 5th gear, but with a 28" diameter tire and a 2.73:1 rear gear your 2000 RPM would be going down the highway at 90 MPH if 5th gear is a 0.68 OD or 77 MPH if a 0.79 ratio 5th gear. Taller tires (likely) would increase these impressive "highway speeds".
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12 '52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
