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Old 11-21-2010, 04:24 PM
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8.5 posi unit

I just picked up a 8.5 housing to build for my Nova. This may sound crazy, but what posi units are best for the money. I don't have a big budget and want something pretty strong. Are the GM ones good, or should I go Eaton or Detroit Locker or what??? I got a 383 w/ TH350 and may run a trans brake in the future...

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Old 11-21-2010, 04:33 PM
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My vote is for an eaton posi unit. I have an 8.5 ten bolt in my C-10, with an eaton posi unit built with advice from Big Gear Head. I would never use an G.M. Governor Loc unit.
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Old 11-21-2010, 05:10 PM
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The GM Traction Lock that was used in the car 8.5 rear ends through '81 was a good unit. This is thee one with the S shaped spring in it. Parts are no longer available for it, so if you have one with good clutches in it then use it. If it's worn out then it's no good. I like the Eaton Posi best, but on a tight budget the Duragrip is hard to beat. It's just like the Eaton Posi except it used a different clutch material. The Duragrip uses a Rabestos material similar to the Ford Traction Lock and it's about $60 less than the Eaton Posi.

If you get the money later to build a good rear end then I recommend getting a 30 spline Eaton Posi, a set of Moser 30 spline axles and upgrading the whole rear end. This makes a very good, strong rear end. I've built many of these and as far as I know none of them have broke.
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Old 11-21-2010, 06:49 PM
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which Eaton?
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Old 11-21-2010, 09:25 PM
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Eaton Posi, not the Eaton Governor Lock. The others are not actually Eaton, they were bought when Eaton bought Tractech.
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Old 11-22-2010, 02:41 PM
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Quote:
Originally Posted by 19nova69
which Eaton?
28 spline Eaton part# 19557-1

If you decide to upgrade to 30 spline. Eaton part# 19559-1
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Old 11-22-2010, 03:12 PM
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could always stick a power traxx in an open carrier. that would be the easiest, as theres really no set up needed
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Old 11-22-2010, 06:37 PM
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whats a power traxx??
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Old 11-22-2010, 06:54 PM
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Quote:
Originally Posted by 19nova69
whats a power traxx??
http://www.powertrax.com/powertrax/noslip.html
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Old 11-22-2010, 07:24 PM
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it says it won't fit in a factory posi housing. How is the GM - Eaton style carrier?
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Old 11-22-2010, 09:10 PM
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The Power Trax kits only fit in standard differential cases. The Eaton Posi is a great street/strip differential. The Eaton Governor Lock is fine for a stock truck, but not so good for abuse.
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Old 11-23-2010, 07:39 AM
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I've seen GM Posi's that say they are "Eaton style" are those any good?
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Old 11-23-2010, 09:36 AM
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Eaton makes the Governor Lock and the Posi. Posi is Eaton's trade mark name for their clutch type limited slip differential. The Eaton Posi was used in the '60s and early '70s in the 10 and 12 bolt Chevy car rear ends and a few 12 bolt truck rear ends. The Eaton Governor Lock was used in almost all truck rear ends that got a limited slip differential, and it was used in a few cars through the '80s with the 7.5 10 bolt. The Hummer H2 and H3 got the newest Eaton E-Locker. As far as I know these are the only Eaton differentials that GM used in production cars and trucks.

Many ebay sellers lable their Governor Lock as a Eaton Posi to trick people into buying them. Many people don't know the difference until it's too late.
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Old 11-23-2010, 04:29 PM
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How can you tell by looking at them which is which? The guy that's selling me the housing says he has a GM Posi that is Eaton style.
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Old 11-23-2010, 04:47 PM
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Eaton Posi

Eaton Governor Lock
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