Truetrac fitment?

[WanaBa442]

So, was poking around Summit and peeked at the listing for a posi: https://www.summitracing.com/parts/dtl-912a317
Looking at the "customer questions" I see they say it'll fit a Monte Carlo, but not a Cutlass 7.5??
Unless you plan to run the stock 2.oh-too-low gear set, why wouldn't it fit the Cutty rear?
Spline count? That's all I could think of...….
This, with a set of upgraded axles, would handle a couple hunnert ponies OK.

 

[pontiacgp]

Thy have their applications screwed up

Axle Model: GM 7.5 in.
Axle Location: Rear
Make: PONTIAC
Beginning Year: 1988
Ending Year: 2002

 

[xylorex]

below is the link to the eaton catalog, our cars are on page #6.

https://www.eaton.com/content/dam/e...ormance-differential-application-guide-en.pdf

 

[WanaBa442]

So, which one would this be?
Listed as a 7.5 GM ( was in a 93 Firebird 10 bolt) but doesn't look like the Eaton catalog choices??

 

[79 USA 1]

Looks to be a Eaton Trutrac. Their catalog shows a picture for a rear other than a 7.5. Below is the link to Toms Differentials, and the Eaton Trutrac looks like what you have in the box.
http://www.tomsdifferentials.com/2011catalog/Pages36-38.pdf

 

[pagrunt]

Looking at the "customer questions" I see they say it'll fit a Monte Carlo, but not a Cutlass 7.5??
Unless you plan to run the stock 2.oh-too-low gear set, why wouldn't it fit the Cutty rear?

For some odd reason in the aftermarket world they don't know that a Cutlass is the same A/G as the Monte & the other A/G cars. It's our own little conspiracy in the world.

 

[WanaBa442]

Oooooh, a secret society of a G-body sub-cult!!
Cutlass Brotherhood, Unite!!!
Ruled by the High Command of the 442,
we lowly 7.5 plebians vow to aspire to 8.5 greatness........

SO, that said, I need to see what spline count this thing is..

 

[79 USA 1]

SO, that said, I need to see what spline count this thing is..

Spline count refers to number of splines on the axle end which mates with the carrier you purchased. If what you have is from a 93 Firebird it should take 28 spline axles, Your Cutlass would have 26 spline. You need new axles!


When I installed a Detroit Locker in my 79 Monte Carlo I used a pair of 28 spline KA axles from Tom's Differentials. Should be the same as the 28 spline axles used in the 442 and Grand National 8.5"s

 

[WanaBa442]

Yeh, axles would be part of the package. New bearings etc, just need to decide if the carrier series will support my ratio choice with a TH350...

 

[xylorex]

i'm doing my rear end next, this is my parts list. this should be close to what you're trying to do.

moser A102801 28 spline axles
detroit 912A317 truetrac
Richmond Gear 83-1016-M Differential Mega Kit
Richmond Gear 49-0046-1 3.73 Ring And Pinion
aluminum cover --- havent decided on this one yet