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Discussion Starter · #1 ·
I got a 67 caprice with the stock 12 bolt rearend. I was thinking about upgrading since all I can do now is do a burner with one wheel. Was gonna get a posi but not sure on which brand or if to get used or new. Thoughts and advice on what you think I should do/get would be greatly appreciated.
 

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If I were you, I would go ahead and build the rear completely. Do it once and be done. I would get some Moser axles, a detroit tru-trac differential and some new gears. Add a bearing support diff cover and go to town! When my 8.5" rear blew up in my 98' GMC I did all this to it. Figured I didn't want to go through it again so upgraded EVERYTHING! I loved the Tru-Trac differential because it is basically a helical gear limited slip. Instead of most limited slips that use clutches (weaker), the Tru-Trac uses a gear set, almost like a real locker but it only engages when you need it. Here's what it states on their website:

"The Detroit Truetrac was the first helical gear differential ever introduced into the automotive aftermarket as an Eaton brand. It remains the leading helical gear-type limited slip differential in the industry. Detroit Truetrac's proven helical gear design eliminates the need for wearable parts, resulting in maintenance free traction recognized not only for its toughness, but its smooth and quiet operation as well.

Proven design, low cost and effective performance all make the Detroit Truetrac limited slip differential the ideal choice for a wide variety of vehicle applications. No maintenance - Just Traction"

I did axles, 4.56 gears, tru-trac and a Moser diff cover. I beat the hell out of the rear and it's still standing today, probably a good 20K on it. Or if you want, you can just sell me the 12 bolt :)
 

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I Personally like the Eaton unit's.They're fully rebuildable if ever needed. Yukon also has a unit out thats called Duragrip. It's a copy of the Eaton but has a Nodular case and they claim better clutch's. It's actually a little cheaper than Eaton,and it's a great unit also.
 

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prostreet6t9 said:
I Personally like the Eaton unit's.They're fully rebuildable if ever needed. Yukon also has a unit out thats called Duragrip. It's a copy of the Eaton but has a Nodular case and they claim better clutch's. It's actually a little cheaper than Eaton,and it's a great unit also.
I have all Yukon, DuraGrip, axles and gears. No problems so far.
Eaton style's a better choice than TrueTrac if much strip use is planned.
 

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Are you serious? I've seen tru-tracs on 8 second rides. A clutch type posi is better than helical gears? I've never heard that one before. The Eaton is a good unit and totally rebuildable which is cool but going for the gear unit is for durability more than ease of replacement.
 

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I'm not saying Eaton isn't a good unit, it's an excellent piece, nice warranty and fully rebuildable. But can you really say it's stronger than a Tru-Trac or better at the drag strip? I know guys cutting 1.32's on Eaton's but also on Tru-Tracs. The Tru-Trac is heavier than the Eaton Posi (both made by Eaton) mainly due to all gear driven and no clutches. I've had both and liked both but preferred the Tru-Trac myself. The Eaton was in my 87' Camaro that went 11.90's on motor, the Tru-Trac was in a 98' Z71 running 33x13.50 Swampers, Vortech V1 and a small NX kit and hit 12.80's. It was more of a offroad/dd truck but liked to take it to the strip when I had time just for fun
 

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RamAirZ said:
I'm not saying Eaton isn't a good unit, it's an excellent piece, nice warranty and fully rebuildable. But can you really say it's stronger than a Tru-Trac or better at the drag strip? I know guys cutting 1.32's on Eaton's but also on Tru-Tracs. The Tru-Trac is heavier than the Eaton Posi (both made by Eaton) mainly due to all gear driven and no clutches. I've had both and liked both but preferred the Tru-Trac myself. The Eaton was in my 87' Camaro that went 11.90's on motor, the Tru-Trac was in a 98' Z71 running 33x13.50 Swampers, Vortech V1 and a small NX kit and hit 12.80's. It was more of a offroad/dd truck but liked to take it to the strip when I had time just for fun
Honestly I think they're pretty close in strength and durablity. The down fall of the Tru-Trac is,if it breaks it's spendy and sometime's it's cheaper just to get a new unit. The Eaton or Yukon will take just as much power and if it ever does break it can be fixed with less money.

I've seen more breakage in the Tru-Trac and it suck's when I have to tell a customer he needs to buy a new unit.
 

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I've seen other tests which show the DuraGrip and Auburn doing much better than these. I think it depends on whos' independent test you look at. :thumbup: Also you don't know what clutches or springs were used in each unit.
 

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I agree, if the tru-trac does let go compared to the eaton, the eaton posi would be cheaper. I've seen a few guys on the NMRA boards bust the Eaton cases though, but that's not a common thing. I talked to a rep awhile back that said the tru-trac should go 8.0's no problem but I HAVE seen them break before that but again rare. There are alot of things that could break a rearend but just design wise, a helical gear set compared to a clucth disc "should" be stronger all other factors taken away. That's an interesting test they have there. Good info
 

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Thr tru-trac just might be able to run in the 8's. One problem with that is, your axle spline is limited on the tru-trac. With the Yukon or even a real Detroit you can go bigger on the axle spline. I don't think I would wanna try and run that fast on a 30 spline axle.
 

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Discussion Starter · #16 ·
Wow thanks for all the info. This car is only going to be for the street not for drag racing so probably gonna go with either a yukon or an eaton. I like that they're rebuildable if anything happens. Thanks for all the help!
 
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