The Stovebolt Site Forums The Shop Area Driveline fifties car versus truck differentials

If I wanted to exhange a 4.11 geared '53 truck rear end for one from a '54 or earlier chevy car, other than the lug differences, anything else I should watch for, will they work with the stock truck torque tube driveline? Are the cars a "milder" rear end gear (guessing they are)??
If I could interchange, I'm betting those car rear ends would be dirt cheap at a salvage yard if I could locate one (I'm figuring likely $100) versus buying a repro ring and pinion (don't know how much they cost, but surely more than that).

The '54 and earlier car rear ends came with a 3:70 ratio or a 3:55 ratio. The 3:55 came in cars that had a powerglide transmission. The rear end for a car is different than the pick-up rear end. Not saying that you couldn't fabricate it to be used. Unfortunately many of the early cars also came with a 4:11 rear end ratio and those guys are buying the rear ends to do the same thing you want to do and that is keeping the price up on them.

I put a 3.5 pass rear end in a AD truck a few years back. It did not fit all that well. The pass axle width is narrower so I had to use wheel spacers.
Your better off using Patrick's 3.5 conversion for the truck diff.

Thanks for the info, that sets me straight.

Yeah the biggest thing is width of the axle. I think cars are 58", and trucks are 61" center to center of tire tread. I learn the hard way on that when I bought my truck. Not knowing it had a car rear end in it, i cut the side wall out of a tire causing a blowout..... exciting to say the least. Then I knew why they had hubcaps on the wheels of it, 6 bolts front 5 rear...... The car axles aren't as heavy either as the truck.....

John

Can you elaborate on this Dave? My understanding was that the torque tube length was where the majority of grief showed up with this plan. Thanks.

The length of the torque tube is an issue. The tires were ahead of stock to get the u' joint in the right place. This was done before Patrick's sold his 3.5. I would not recommend the set-up.

I didn't remember the torque tube being an issue, just the width mainly. If I remember the mounts looked like they had been moved on the differential, I guess to line up with the mounting pivots on the truck springs.....

John