P case.

pvs409

Well Known Member
Supporting Member 7
#2
standard ratios for 1955 to 1964 Chevys rear end built by GM are/were
3:08, 3:36, 3:55, 3:70 , 4:11 and 4:56 plus 5:13.

All rear ends I have had over the last 40 years were 3:70 ratio not 3:73.
Paul
 

Woody62

Well Known Member
#3
Cool. Thank you for correcting me. I am still looking for a P case to purchase. Regardless of gear. If you have someone who might be willing to part with one I would be interested as I am tired of th 4:11s currently in the car.
 

4onthefloor

Well Known Member
Supporting Member 1
#7
Thats pretty cheap for a bare P case. There are some folks asking a ton more for the early year Corvette cases. I have a 1957 Chevy 4.11 posi that is a pre-P case. Probably out of a 6 cyl overdrive. If it was stamped for Corvett it would be worth a ton.
 

Don Jacks

Well Seasoned Member
Supporting Member 3
#11
The "P"cases aren't any stronger than the standard cases.They used the same metal.This for all 57-64 units,55-56 are thinner,weaker.
 
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Carmine

Well Known Member
Supporting Member 7
#12
Just my opinion, but I think the "P" cases are for bragging rights. I had 2 of them and sold them both. I presently have an open 3.36 rear in my 409 powered '62. I also have a stock posi unit sitting on the shelf. Not sure how I acquired that. My plan is perhaps some day take the rear and posi unit to someone reputable and let them mate them together. I'm sure some grinding will be involved from what I read, but personally, I don't care. I also wouldn't have a problem using an Eaton or Auburn posi unit in an original open rear. Again, some grinding involved, so what?? If anyone is happy with paying that kind of money for an empty "P" case, then I'm happy for them, Carmine.
 

Carmine

Well Known Member
Supporting Member 7
#14
Stay away from Auburn if you're going any where near a drag strip.
Thanks Don. No drag strip for me. I'm not sure I'll even use the posi unit in my 3.36 gears. I've never spun the rear tires. No desire. I might have run up the rpm's a few times, but no hole shots. Can't take the chance of launching this engine, Carmine.
 

DonSSDD

Well Known Member
Supporting Member 2
#15
Not much grinding at all to fit a posi and just as strong as a stock posi case and way easier to find than a P case. Read Tom Parsons posts on CT as Paul said, lots of great pictures.
 

Carmine

Well Known Member
Supporting Member 7
#16
Not much grinding at all to fit a posi and just as strong as a stock posi case and way easier to find than a P case. Read Tom Parsons posts on CT as Paul said, lots of great pictures.
Thanks Don, I have read that post previously on CT. Alot of info there. I've also seen diagrams showing where to grind a particular rib some. I think it's something I could myself if I wanted. Not sure what I'm going to do. I don't necessarily need a posi rear. I don't beat this car at all. The present 3.36's are out of a '57 with about 40 thousand miles on them. They work fine. No noise and I like the ratio. I have to learn to leave things alone or I'm going to get in trouble, Carmine.
 
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