69 Rear End Code Stamping

[HOT3O2]

Hey Guys,
Has anyone come across or heard of an original rear end that didn't have code stamping on a rear end? I have a 69 Z28 (12B Build date) And for the death of me I can't find any stamping on the axel tube. I've seen pictures of where it's suppose to be. Got under there with a flash light and cleaned the old paint off and can't seem to find it any where. I know the rear end is original to the car. I've owned it for 35 years. Any ideas?  Thanks, Rick

[x77-69z28]

sometimes it is a little higher or lower on the tube, but have never seen one without it. if it makes you feel any better look for the casting date on the back of the center section of the rear. i believe it is the left side upper part.

[babaron]

It can be extremely hard to find.  I've seen mine several times before and I still have a very hard time seeing it whenever I go to find it, even though I know where it is .

[HOT3O2]

Thanks, I did find the casting number. I will give another shot to locating the code stamping. as you said, it's got to be there some where. I appreciate the help.

[x77-69z28]

does the date code line up with the build date?

[HOT3O2]

Yes it does. It's a late Nov. casting and the car is a 12B. I would like to know what gearing the rear end came with.

[JohnZ]

Yes it does. It's a late Nov. casting and the car is a 12B. I would like to know what gearing the rear end came with.

The only way to verify the original gearing is from the axle tube stamp or the Protect-O-Plate.

[HOT3O2]

Thanks John, I'll keep on looking. It's got to be there some where.

[x66 714]

I've seen a few over the years that were stamped on both axle tubes. Some I've seen at almost 12:00 position. Happy hunting, Joe

[HOT3O2]

Thanks Joe, I'll keep that in mind. It's like a good mystery. The hunt goes on.

[rich69rs]

Yes it does. It's a late Nov. casting and the car is a 12B. I would like to know what gearing the rear end came with.

The ring gear is also date coded, with the GM part number, gear ratio, and month / year the ring gear was manufactured stamped on the OD of the ring gear.  You obviously have to take off the diff cover to see the OD of the ring gear.  As JohnZ stated, this doesn't confirm original gearing, but it does help you date it.

Attached pic shows an example.  The first part number is the GM part number.  The next two numbers, 15 and 41 are the number of teeth on the pinion and then on the ring gear.  41/15 = 2.73, which is what this open rear end is.  The next two numbers 9 68 are the date code, i.e. Sept 1968

[rich69rs]

second view

[My68SS]

Ahhh!!! more dismantling for more numbers that I need to check!!! 

[HOT3O2]

Thanks Rich, I'll keep that in mind. It's nice to have something to fall back on.