Hey guys...Newbie here. I just picked up a 71 442 numbers matching car (at least the vin, engine, and tranny so far). I have a 402227 rear but from what I read 70 was the last year for that rear. The car has power windows and ac with a column shift. Kind of a weird set up but also nice. I am wondering if Lansing just used up what they had and installed a 12 bolt type o anyway. Also where is the axle stamp commonly located. I have scuffed the tube to the right of the diff cover and the opposite side with no luck. Maybe I need to scuff some more.

 

keep trying...sometimes the stamp is lightly done. about 1/4" tall capitol letters.

sounds like a good car, show us some pics when you have time.

 

It is often on the passenger side axle tube on the back side about mid way between the spring perch and the center section. It is faint often and upside down.

Keep cleaning and trying it is very faint often.

 

Here's a picture of one of my O-Type rears showing the location of the stamped code. It can be VERY hard to see due to rust, dirt, oil buildup, etc.
The blob of silicone RTV at the left side is where the axle vent hole is.

https://classicoldsmobile.com/forums...tial-code.html