The Stovebolt Site Forums The Shop Area Driveline Deciphering rear end codes

Can somebody decipher this for me?
I’m trying to get a huge joint for it and I was told it was a particular model GM but the U joints I got for that year wrong.
I’ve got three pictures below of numbers on the center section and the rearend housing cover…….. I would appreciate it, thanks, Joe

There should be another code on the axle tube. That number will give you the information you need. Usually located on the passenger side on the front of the tube. I think it is about three inches from the differential.

I’ll climb under the truck tomorrow and see if there is any that might be readable…thanks, joe

You may need to wire brush it to see the code.

Joe - Those stamped codes are also sometimes located more towards the top of the passenger side tube on some axles. Your last picture makes this look like a GM A-body 10-bolt.

Here's a great resource article on GM 10 bolt identification and upgrades. There are even charts with decoding info to help ID the axle. Charts are divided between 1970 and earlier and 1971 and later axles.

Let us know what you figure out.

The cover looks passenger car style. Does it have 5 wheel studs?

The casting number 3917123. 1968-1969 Chevelle


Generic Rear Axle Information

1968 Chevelle Rear Axle Identification

Looking at the information from the Chevelle site, early 10 bolt, '67-'69, Chevrolet only. It should be a standard u-joint used for years. BOP axles of from those years use a bigger cup on the u-joints and won't fit the Chevy, but you can buy a adaptor u-joint if you have a BOP driveline and Chevy axle.
Pull the cover off if you really can't decide on the year, the ring gear will have the date stamped on it along with the ratio.

The early cars from '64-'67 used a narrow rear axle, the bodys changed in '68 and used wider axles. Yours being narrow would fit the truck better and keep the tires under the fenders.

Thanks folks, I’ll use this info and hopefully it’ll give me the correct information to get the right U-joint…Thanks again,joe

I took the info that I was given and looked up a 69 Chevelle rear U-joint and it fit. So that I remember what it is I’m stamping the year and make vehicle and the Moog part number on the rear end housing. Thank you very much folks,joe

Great deal Joe! Glad to hear the problem is figured out and you left yourself a permanent note for future use.

Here's a picture of mine. It's on the top of the passenger side of the axel. The part about the spline count I added myself.

That area on mine had had a grinder ran across it when removing all the mounts that weren’t necessary. So it probably disappeared because of that. But thank you, Joe.