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Posi Rearend

2K views 7 replies 5 participants last post by  big gear head 
#1 ·
Positive Traction rearend

I would like to put posi trac on my pick up .I have a 1987 GMC Rally 1500, 350(stock) and TH 350. Is as simple as going to the junk yard and pulling the gears from a 4x4 rear end or do I need to get a whole new rear end.

Thanks in advance!
 
#2 ·
Im looking to replace my stock rearend with posi traction. I am looking at one on craigslist from 65 Chevy truck with a 3:07 ratio. Will it be compatible for a 1987 Rally 1500 pick up. Also I im pretty new at all of this and I dont quite understand what the ratios mean.

Please advise
Thanks
 
#4 ·
GMC R1500

I merged your two threads since you ask the same question

You need a carrier that is a design for transfer of power to both axles.. this is often called a positraction carrier , limited slip is another term used.

You must have the correct design carrier to fit the differential you have in the vehicle.

It is not simple to install for the novice , it must be installed and setup correctly for the ring and pinion gears to operate
 
#5 ·
Your '87 will have the 8.5 10 bolt rear end with 28 spline axles. The '65 will have the 12 bolt rear end and trailing arm suspension. They will not interchange. You can install a limited slip (posi) differential into your rear end. You need to know what your gear ratio is before buying anything. If you have a 2.73 to 4.10 gear then you need a 3 series differential. If you have a 2.56 or 2.41 then you will need a 2 series. In '89 they switched to 30 spline axles, so you need to be sure that you get a 28 spline differential. This is how you install it. http://www.nastyz28.com/forum/showthread.php?t=19773&highlight=install+posi

You might want to look at this. http://www.hotrodders.com/ads/showproduct.php?product=6941&sort=1&cat=20&page=1
 
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