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Can any one tell me or tell me where to go to find info on the rear end I pulled out this last weekend?
I pulled it out of a '87 Firebird. The width is 62" the same as the torque tube I pulled out of my '51 3100. With the drive saft off I turned the 3rd member flange and both drums turned in the same directions. Does that means it's a posi? While turning the flange on the 3rd member, it turns approx. 3 1/4 turns to one one of the drum. I'm hoping this rear end will work in my '51. What do you think?

I would at least take the back cover off and check the teeth out. You have the right width and it should fit and work. My 80 Camaro had to be rebuilt.

I'm going to try to get to pulling the back cover this weekend if I have time. So with out taking the cover off how do I know it's a posi or not? So far I found these numbers on the long tube. 2HLC312 1. I tried looking it up on differant sites with no luck. With the drive saft off I turned the 3rd member flange and both drums turned in the same directions. If I turn one drum the other side turns in the opposite direction.

Sounds like it isn't posi but I'm no expert on what it should do in those conditions. I'm surprised none of the rear gurus haven't chimed in yet. Perhaps soon...

If the drums turn in opposite directions it's not a posi.

What you are saying is if I turn the drum in one direction the other drum should rotate in the same direction?

Hi Terry,

When you turn the pinion flange both wheels should rotate in the same direction. Just a heads up....when you pull the cover and check out the numbers stamped on the outer edge of the ring gear copy them down on apiece of paper. It's real easy to jump to conclusions about the actual R&P ratio. I was offered one by a yard that swore it was a 3.42 by the numbers. I did the spin test and found it was actually a 3.23.

The easiest way to determine the ratio on your non-posi is to block one side so only one drum will turn. Mark the unblocked drum and the yoke and turn the drum 10 full 360 degree turns. Count the number of times the yoke spins 360 degrees. If the yoke spins a little more than 34 times you'll have a 3.42. A little more than 37 times will be a 3.73.

By turning the drum a full 10 times you'll increase your accuracy over just one turn.

If the gearing is correct for your particular transmission the diff will work fine. The axle tubes on the Camaro/Firebird diffs are only 2-5/8" in diameter so you'll want to tack on a couple layers of 1/8 X 1" straps under 3" u-bolts to get a good tight fit. I bought my narrow perches from the trailer section of Tractor supply. Custom 2-5/8" U-bolts and base plates to fit the smaller diameter axle tubes were outrageuosly expensive.

I'm running a 62" wide 88 drum 3.42 behind my .72 T5 and the gearing is great. With a little more info on your transmission and engine choice we might be able to give you some more accurate suggestions.

Dave

read this link throughly
https://www.stovebolt.com/ubbthreads/ubbthreads.php/ubb/showflat/Main/52074/Number/376952#Post376952
http://50chevy.freeservers.com/Suspension_Widths.html#Suspension
this should help you

Dave, I'm using a 327 cu inch eng and a turbo 350 in my '51. I was really hoping the rear end out of that 87 Firebird was posi. With the rear end off the ground I turned the third member yoke and both drums turned the same direction, I thought it was a posi. I will not have time to pull the cover until next week. I want to thank all you guys for helping me with this. I know nothing about rear ends.

Capitol ,
I did a little research on the 87 Firebird ...an have come up with no info that a Posi Trac rear was even offered in that vehicle .
Not sayin there werent any ...but I would bet if there were it would have been in the Firebird Formula or Trans-Am ..series .
the later 80's was more focused on looks than performance.
Just my 2 pennies