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Old 10-21-2019, 09:23 PM   #1
Speedracer39
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Which brand of posi

Iím running a 496 in my 72 c10 with a turbo 400 and 373 rear gear. I do not want to go to a overdrive trans but Iím looking for a more highway friendly rear gear. Planning on going with 308 but looking for advice on what brand of posi is everyone using with good luck??
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Old 10-21-2019, 09:36 PM   #2
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Re: Which brand of posi

I like eaton
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Old 10-21-2019, 10:30 PM   #3
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Re: Which brand of posi

I have used Eaton on two rear ends with great results.
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Old 10-22-2019, 11:04 AM   #4
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Re: Which brand of posi

Eaton...Eaton was OEM back in the day. I run them in both my 72's and have yet to wear one out. I have one with 150K + miles on it and it still works great behind my built 427 BBC with a 4:56... You'll like the 3:08 for mileage and keeping the rpm down on the highway. That 496 with the 3:08 will stress the u-joints, yokes, and carrier bearing a little more. Mine bent the trailing arm pearches on the axle housing hooking up with 14" inch wide Mickey Thompson Sportsman Pro's...Replaced them with Captainfab's pearches and no problems since...
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Old 10-23-2019, 10:52 AM   #5
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Re: Which brand of posi

Tru-trac all the way
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Old 10-23-2019, 02:02 PM   #6
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Re: Which brand of posi

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Tru-trac all the way
Thatís what I use. No parts that wear over time. Really stout construction. No additives needed.
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Old 10-23-2019, 02:18 PM   #7
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Re: Which brand of posi

I have 2 acquaintances that have utilized the Tru-trac units. A bit spendy at first but worth it in the long run.
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Old 10-23-2019, 11:20 PM   #8
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Re: Which brand of posi

Simple, eaton
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Old 10-24-2019, 12:11 AM   #9
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Re: Which brand of posi

Yukon makes an exact copy of the eaton unit, great quality and sometimes with rebates.
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Old 10-24-2019, 03:17 AM   #10
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Re: Which brand of posi

Yukon is china, be advised
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Old 10-24-2019, 04:25 PM   #11
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Re: Which brand of posi

Sorry to hi-jack.. but i just got in a new spider gear kit for the 67 in working on currently. It has the Eaton Posi unit and i am needing to replace the chewed up spider gears and everything that goes with doing the task. Is it possible one of yall has a link for a good write up on bssically a full rebuild for the 12 bolt truck rear end? Tools required? Think all i need is a mag based dial indicator.. But...I have never taken on the task before, n just want to be confident with fhe finished result. I appreciate any helpful advice. (Pic Below) 6.0/80e, cam, converter, Single stg. N≤O.. Once i get the 12bolt done i can finish tuning it 🇺🇸
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Old 10-24-2019, 04:42 PM   #12
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Re: Which brand of posi

http://67-72chevytrucks.com/vboard/s...d.php?t=509262

Answered my own question! 🍻
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Old 10-24-2019, 11:50 PM   #13
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Re: Which brand of posi

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Tru-trac all the way
Just put a Tru-Trac in my 72 this past summer and am happy with it. I find on cornering it keeps both wheels gripping the same.
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Old 10-25-2019, 11:58 AM   #14
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Re: Which brand of posi

I put an Auburn Posi, new 3.08 ring and pinion, and new axles in my 71 rear end. With labor it was $1900 bucks. I'm very happy with it.
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Old 10-25-2019, 06:45 PM   #15
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Re: Which brand of posi

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I put an Auburn Posi, new 3.08 ring and pinion, and new axles in my 71 rear end. With labor it was $1900 bucks. I'm very happy with it.
I have to ask what are you running for a engine and are you happy with the 308?
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Old 10-25-2019, 07:03 PM   #16
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Re: Which brand of posi

I'm running a 355, 350 bored .030 over, with domed pistons. Edelbrock manifold, 600 CFM carb, and cam is a little over stock. I'm guessing maybe 270 HP. Tubo 350 trans. The truck is plenty peppy and does well at 70 MPH on the interstate.
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Old 10-26-2019, 10:52 PM   #17
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Re: Which brand of posi

If you want a clutch-style Posi, Eaton was the original supplier and is basically identical nowadays save for the clutch material (now that are carbon instead of what I am sure was some type of asbestos-containing stuff, back in the day). Plenty strong, but does need a friction modifier. Very streetable, soft engagement.

Detroit TrueTrac is a bit more aggressive, no wearable parts, no friction modifier, stout as heck.

That being said, I put an Eaton in mine when I rebuilt it. Can't go wrong either way, but having driven both, I prefer the more tame street manners of the Eaton.
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Old 10-27-2019, 05:31 PM   #18
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Re: Which brand of posi

I put an Auburn posi on the 3.73 12 Bolt rear in my '67 K/10 Suburban around 1995. Sub was rigged with a 454 BBC/TH350/NP205/ on 33X12.50X15 meats.
In late 1998, it had an engine fire, and I towed it home. It sat until 2012, when I blew up the factory 12-Bolt Eaton posi under my '71 GMC Jimmy. So my drinking buddy and I cannibalized the Auburn posi 12-Bolt off the Sub and fit it on the Jimmy.
Yes, there were spring perch issues. The shorter [width-wise] '67 Rear went on under the '71 OK, but we could not get the narrower-width springs to stretch out to mate up to the '71's Rear.
The Sub's Auburn posi rearend still works great on the GMC, until I can get the factory Eaton Rearend rebuilt and back under the Jimmy.
If anything the narrower stance gives the Jimmy an even tighter turning circle.
The first step to the Suburban Rebuild Project, will be to rebuild the Eaton posi.
The '68 C/10 Stepside, L6 292/SM465/12-Bolt 3.73 w/Eaton posi has been running good for 34 years.
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Old 10-27-2019, 07:22 PM   #19
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Re: Which brand of posi

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Originally Posted by CMars45000 View Post
If you want a clutch-style Posi, Eaton was the original supplier and is basically identical nowadays save for the clutch material (now that are carbon instead of what I am sure was some type of asbestos-containing stuff, back in the day).
The OEM clutches were steel.
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Old 10-27-2019, 09:39 PM   #20
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Re: Which brand of posi

Keep in mind the OEM installed Eaton was the G80 Gov-Loc, which in all reality is complete junk. It's a centrifugal weight activated locker. They have tendencies to be inconsistent, noisy, and usually they unlock them selves when turning to one side vs. the other. They're also very weak, That 496 would make mince meat of them rather quickly. They aren't rebuildable.

Now, the Eaton LSD is an absolutely wonderful unit. They're super consistent, operate quietly, and are very tough. Also, they can be upgraded. in standard form, they come with 400 lb. preload springs and carbon clutches, but can be upgraded to 800 lb springs and Kevlar clutch material. They're also rebuildable. If you wear it out, send it back in the have the clutches and preload springs replaced.

I personally have never dealt with the Tru-Trac, but I've never heard anything negative. I do know they're more preferred in road racing than dragstrip use.

The Auburn unit is a good unit, but isn't rebuildable or upgradable.

Also, if you're interested in better highway manners, a 3.42 gear is also a good option so you don't lose that low end grunt.
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Old 10-29-2019, 07:30 AM   #21
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Re: Which brand of posi

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Keep in mind the OEM installed Eaton was the G80 Gov-Loc, which in all reality is complete junk. It's a centrifugal weight activated locker. They have tendencies to be inconsistent, noisy, and usually they unlock them selves when turning to one side vs. the other. They're also very weak, That 496 would make mince meat of them rather quickly. They aren't rebuildable.

Now, the Eaton LSD is an absolutely wonderful unit. They're super consistent, operate quietly, and are very tough. Also, they can be upgraded. in standard form, they come with 400 lb. preload springs and carbon clutches, but can be upgraded to 800 lb springs and Kevlar clutch material. They're also rebuildable. If you wear it out, send it back in the have the clutches and preload springs replaced.

I personally have never dealt with the Tru-Trac, but I've never heard anything negative. I do know they're more preferred in road racing than dragstrip use.

The Auburn unit is a good unit, but isn't rebuildable or upgradable.

Also, if you're interested in better highway manners, a 3.42 gear is also a good option so you don't lose that low end grunt.
The G80 is a full float unit. The standard 1/2 ton 12-bolt (and 10-bolt) rears use a standard Eaton Posi unit...
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Old 10-29-2019, 08:24 AM   #22
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Re: Which brand of posi

The G80 was only the Gov-Lok after 1973? Before that it was the standard Eaton posi as mentioned above.
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Old 10-30-2019, 08:23 PM   #23
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Re: Which brand of posi

Auburn is good but not rebuildable. The cone style clutch wears into the case making it a throw away. Takes years though.
True trac is very positive, sometimes noisy and sometimes a bit clunky
Eaton is rebuildable and perfect for street use. My first choice.
Yukon, yes, China. That said, I've built many rears at my shop and used many of these with no trouble. Never had a failure and the ring mount surface is always spot on as far as runout. I have one in my (Twin turbo truck).
Don't lose sight of the fact that these trucks don't have any weight in the rear and you will be breaking the tires loose long before you generate enough torque to do damage.
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Old 10-31-2019, 12:33 AM   #24
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Re: Which brand of posi

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Tru-trac all the way
x2...beat them like a mule and they come back for more.
That being said, have an Auburn that was behind a 383 stroker in a 72 2wd and it did great.
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Old 10-31-2019, 05:29 PM   #25
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Re: Which brand of posi

Tru-Trac for the win.... all day long.
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