Good streetable 8.5 posi unit

[79loserbluebu]

Hey all just picked up a 8.5 rear end today. Bought it knowing it wasn't posi, because I have one in the garage. Problem is, it's out of a newer style GM truck with 30 spline axles and the battle is between trying to get axles for a 30 spline, or buying a new 28 spline posi unit.

I'm pretty sure I'm gonna go ahead and get a new differential instead of new axles, so what would be a dependable one to get? The rear has 3.73 gears so we are gonna use those on the new dif. The only two I have been seeing are the Eaton unit and the Auburn. Which would you prefer? Also I don't want to run a spool on the street. I'm taking my time with this build so if it's costs a bit, I'll save and do it right the first time.

Thanks

 

[holtjohn]

how are you gonna make it fit into your bu? or is for your bu?

 

[79loserbluebu]

Yeah it's for my car, it was out of a 442 so it should fit like a glove.

 

[79malibusbc]

if i were you id use the truck posi 30 spline and call moser and order some 30 spline axles cheaper then buying a new posi just my 2cents.

 

[LS6 Tommy]

if i were you id use the truck posi 30 spline and call moser and order some 30 spline axles cheaper then buying a new posi just my 2cents.

x2. Plus, the 30 spline axles are theoretically stronger.

Tommy

 

[79loserbluebu]

Will the newer differential fit in the housing no problems? I have the bearings and everything for the new one. I might as well replace the seals in the rear as long as I'm getting new axles.

I'd probably be looking for some axles like these? #-o
http://www.summitracing.com/parts/MSR-A103004/

 

[Malibu355]

weren't the newer truck posi units know for grenading?

 

[Ed Cannon]

If your wanting a good limited slip for street strip get a Detroit truetrac. Great street manners and I know of guys running in the 8's with them. No maintenance, no clutches, no additives. Jegs has em for around 450+/-.

 

[cutlass389]

Go with the new 30 spline axles UNLESS the "newer truck posi" is a gov-lock unit. If it's a grenade-lock, pull the pin, throw it as far as you can and get anything else.

 

[79loserbluebu]

Well I'm not really sure what kind of unit it is. The car will be street driven with a chance of very light track use. But if it's a turd then I don't want to risk any damage to well, anything. I took some pictures as well as one with the part number though. I haven't been able to track the number down furthur than what it says on the box it came in. It also came with a cover gasket that fits perfectly on the 8.5".
Box: If you can't see or it's blurry, the P/N is 12471391

Rear end

New diff. unit

I really appreciate all of your help. I'm a first timer and hopefully won't be having to do this a second time.