MidShark

Now that I've got my '57 on my lift, I took a look at the rear end center section and see it's a 3789812 with a small "P". There's no casting date on that side, but it looks like a Julian date cast on the passenger side with something underneath it. Just to the left of that you can barely see a light "30" stamped there. I can't find much info on the small "P" casting, as all of the pics I seem to find are of the large one. Could this be a Buffalo built passenger car rear? Over the counter? Was told it was a 4.11, but the yoke goes around about 3 1/2 times, so I'm thinking 3.55 or 3.70 (fine with me). It is the Corvette housing, as the wheel cylinders are tilted forward. Any idea on what I've got here?

62vetteman

There were three cases made. The cases with the "horizontal P" were made in Canada ( pass. car ). The two U.S. cast cases have either a "vertical thick P" or a "vertical thin P" The Corvette only used the "vertical thin P" . DZAUTO ( Tom Parsons ) posted photos of the three cases ( https://www.corvetteforum.com/forums...ification.html ) and further explains the "P" designation in this old post. A 3.55 gear should be about 3 1/2 turns, a 3.70 about 3 3/4 turns.

DZAUTO

That is a Canadian posi rear. It WOULD NOT have been a factory rear for your Corvette-----------------------BUT IT WILL FIT AND WORK JUST FINE!!!!

The 812 case (either USA or Canadian) was 62-64, so VERY POSSIBLY your rear came from a 62-64 Canadian built Chevy or Pontiac.
Since you are in Mich, it is not unusual at all that your rear could have come from a Canadian built that came across some time in the past.
Now, with that thought in mind, is it possible that your car was built for Canadian delivery? Yes. BUT, Corvettes built for Canadian delivery were STILL BUILT at the St. Louis plant and received rears from the Detroit Gear and Axle plant with the thin, vertical P.

MidShark

Thank you both for the info. I knew it was a later rear end and not original to the car, but I hadn't seen markings like that before. Being a Canadian posi makes sense, though, as I purchased the car in Canada. Don't know any history on it up there, though.