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Old 07-03-2019, 11:02 PM   #1
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5 Lug 373 Posi Rear End ??????

Was there a real 373 5 lug Posi rear end from GM using Eaton Gears or were they linited slip ? A guy told me today he had a GM 12 bolt rear with factory Eaton Posi for sale . If its real Im interested in it and also what would it be worth if real ?
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Old 07-04-2019, 01:43 PM   #2
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Re: 5 Lug 373 Posi Rear End ??????

TTT , I know nothing about rear gears but would love a Posi in my next build if its real .
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Old 07-04-2019, 02:09 PM   #3
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Re: 5 Lug 373 Posi Rear End ??????

I'd pop the cover off of it and have a looksee....cant always go on what someone "thinks" it is..
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Old 07-04-2019, 02:29 PM   #4
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Re: 5 Lug 373 Posi Rear End ??????

Thats the problem , I dont know what to look for to tell if its a Posi . Did GM make a true Posi for trucks like the did for Chevelle's ?
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Old 07-04-2019, 02:30 PM   #5
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Re: 5 Lug 373 Posi Rear End ??????

Posi and limited slip mean the same thing to me. If there is a difference, someone post it...

If you know what a posi carrier looks like on a 12 bolt Chevelle, the pickup carrier looks exactly the same!!! Someone post a picture!!!

Posi and limited slip mean (to me) the the gear carrier has clutches in it to allow both axles to turn, when going in a straight line. the clutches slip when going in turns, to allow the axles to "differentially turn".

A locking axle has a mechanical device that senses when both axles are spinning the same RPM and one is not turning as fast, and locks them together, when this happens (my explanation may not sound exact...)

If there's more than one type of rear end that's not a standard open rear end for a 1/2 ton, I'd like to know...

To purchase a 5 lugger rear, as you describe, most folks know what they have. I' m guessing the asking price is over $500.00. Then a question you have to ask, what condition is it in??? Also, If it's been "worked" on, was the work done by someone competent???

If Eaton was the manufacturer of the gear carriers, I have no idea. Seller might be slinging bull to sell for most $$$, an every day thing...I HATE...
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Old 07-04-2019, 03:34 PM   #6
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Re: 5 Lug 373 Posi Rear End ??????

I have asked him for pics inside , he thinks its original and he also thinks its worth $1000 . I am looking at another one that I know has all new parts inside but waiting on price on it . May be more than Im willing to pay .
I keep gathering parts for a truck thats not even in my possession , Body Shop Jail . I cant wait to build this truck .
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Old 07-04-2019, 03:39 PM   #7
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Re: 5 Lug 373 Posi Rear End ??????

Ok...pull the cover..if you see springs and plates like in 1st pic then it's a posi...
If theres nothing but side and spider heads then it's a open diff as in 2nd pic...
You also know the drill...take a pic and post it if your unsure...somebody will know what it is..
And yes ..older trucks could be ordered with a locker...newer ones got the g80
I wouldnt give a grand for a unknown condition rear...if it was all fresh itd be worth it
Also if its 3.73s it should have 41/11 stamped on the ring gear
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Last edited by mongocanfly; 07-04-2019 at 03:45 PM.
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Old 07-04-2019, 03:57 PM   #8
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Re: 5 Lug 373 Posi Rear End ??????

Thanks Mongo , those pics will help a lot when he sends pics . Im more interested in the local one to me that My buddy has with everything new inside , just waiting on details and price on it .
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Old 07-04-2019, 04:00 PM   #9
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Re: 5 Lug 373 Posi Rear End ??????

Sounds like a plan!.....just noticed you crossed the 12000 post mark...congrats...I guess

Also keep in mind that 12b car and truck diffs arnt the same
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Last edited by mongocanfly; 07-04-2019 at 04:07 PM.
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Old 07-04-2019, 08:05 PM   #10
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Re: 5 Lug 373 Posi Rear End ??????

Quote:
Posi and limited slip mean the same thing to me. If there is a difference, someone post it...
Well sort of. "positraction" was a term used to sell GM limited slip differentials in the 1960's. Not any different that Chrysler using "sure grip" for their ads or Studebaker using "twin traction".

There are different types of limited slips and their cousin "locking differentials"
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Old 07-04-2019, 09:34 PM   #11
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Re: 5 Lug 373 Posi Rear End ??????

Thanks everyone for the much needed education , Im buying the one from my Buddy near me that is much more affordable .
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Old 07-04-2019, 09:36 PM   #12
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Re: 5 Lug 373 Posi Rear End ??????

great!..at least you know what your getting that way...
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Old 07-05-2019, 11:44 AM   #13
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Re: 5 Lug 373 Posi Rear End ??????

Quote:
Originally Posted by Bigdav160 View Post
Well sort of. "positraction" was a term used to sell GM limited slip differentials in the 1960's. Not any different that Chrysler using "sure grip" for their ads or Studebaker using "twin traction".

There are different types of limited slips and their cousin "locking differentials"
Yeah, Pontiac had another word for theirs, can't remember it at the moment...
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Old 07-09-2019, 08:08 PM   #14
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Re: 5 Lug 373 Posi Rear End ??????

Pontiac called it "Safe-T-Track"

Cadillac = "Controlled Traction"
Olds = "Anti-Spin"
Chevy/GMC = "Posi-Traction"
Chrysler = "Sure-Grip"
Ford = "Traction-Lock"

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Old 07-12-2019, 03:48 PM   #15
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Re: 5 Lug 373 Posi Rear End ??????

That's why GTO's are safer than the rest.
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