The Stovebolt Site Forums The Shop Area Engine Shop what is the range of ratios and interchangability of diffs

I'm interested in changing the ratio of a 3/4 ton R/e . IIt looks like they used this R/e for decades so it seems that there should be several different ratios used in the same basic housing. Am I on the right track or dreaming?
Cheers

IF you do a search of this forum, you will learn that your choices are extremely limited. Assuming you have the 4.56 gears, you can get the pumpkin out of a 64-72 with 4.10 gears. A few 3.73s are out there, but about as scarce as hen's teeth.

Another option is to go with a later model differential, which is about 3.5" wider. Width is partially offset with newer rims which have more setback. With a 12 bolt, you can get 3.73 gears and still have a round housing. The bulletproof 14 bolt has a flat sided housing, but can be found with 3.42 gears. Cost around here for the 14 bolt is in the $300-350 range, 12 bolts are a lot cheaper.

There is also a new 3.90 gear set available which can be installed in some of the more modern versions of the pumpkin. American Classic has them listed as if they install right into the AD trucks, and that is incorrect. They install into 1959 to ?? pumpkins as stated by their supplier, Randy's pinion and gear.

T'nix, are you sure about the 3.90 not fitting the AD tonner? When I took the Juggernaut to Randy's they said they could do 3.90's but they would have to make a custom carrier bearing (more expensive and would take a week rather than a day). I'm cheap, and there's not much of a numerical difference between those and the 4.10's I opted for.

4:10 pumpkins are easy to find,,,,, if you look in my garage
I found out that a 10-bolt rear end out of a 79 cadillac Fleetwood Broughm de Elegance has a rear disc brake equipped rear end and measures 61 & 1/4 from wheel mounting flange to wheel mounting flange
The measurements for the 1/2 ton,,47-54 & 55 1st Series Chevy Truck 60-62" And the 55 2nd series to 59...55-59 Chevy Pickup 62"



I think the 3:73 ratio pumpkins are in big block equipped Suburbans from the 69 to 72 era.

Hedgehog,
that is what I am talking about. The 3.90 gear set is not a drop in for the AD pumpkins. However American Classic lists it as so and I talked to them on the phone. They gave me Randy's number to get more information.

I agree that 3.90 is not much different from 4.11 .