jzee

Hi there, first time on this site, am in the process of restoring my brothers hot rod, a 1937 Pontiac Coupe Deluxe, He had a stroke awhile back and had it in storage for about 5 years. It was a custom hot rod with a Mondello Oldsmobile
508 cu.in. I have very little information on the rest of the drive train except that there is a 3-speed automatic and the rear end we think is GM, not sure?

I have been flat on my back looking at the rear end for weeks and so far I have found stamped on the passenger side ACC 1371, and a casting number on the housing of 1243774. Some sites say it is a Skylark, others say it is a El Camino. Problem is from the pictures I have seen they both have the shocks in the rear of the axle, mine are in front of the axle. It has Coil springs if that helps. measures about 56" BP to BP, 10 bolt, rear cover looks almost flat on top, bottom and sides.

Ratios also are all over the place, some say 2.73, others say 3.08.

Any help would really help, need to replace the pinion seal and all the rubber bushings.

Thank Guys

oldcutlass

Welcome to the site, sounds like a cool car. Post some pictures when you get a chance. Also some detailed pictures of the rear, someone can help you figure it out.

lemoldsnut

That sounds like a Chevy axle number. To find out the ratio you can do this as you lay under it. either pull the cover off and count the teeth. Divide the pinion teeth number into the ring gear count and walla you have it. Or you can mark the drum to backing plate with a chalk and the pinion and rotate the one side two times. The other must stay still (if it is not a positraction rear end) if it is a positraction rear end then let them both turn and it is only one turn. Count the rotation of the pinion. If it is just over 3 it is a 3:08 if it is 2 3/4 turns it is a 2:73 or 2:78 if it is 3 1/4 turns a 3:23 3 1/3 turns a 3:31 just under 3 1/2 3:42 just over 3 1/2 3:55 3 3/4 turns 3:73 just under 4 turns 3:90 or 3:91 just over 4 4:10 and so on.

There is also a casting number on the cast iron center section what is that?

How many bolts hold the cover on? if it has an upside down v in the cover and 12 bolts it is a Chevy 12 bolt rearend.

Hope this helps

Larry