Does anyone know how many splines are on the stock axles of 05-up Mustang GTs? The older GTs used to have 28 splines, but seeing how the latest Crown Vics (with only as much as 250 hp) are getting 31 spline axles from the factory, I figure the S197s should be getting them from the factory as well.

 

Pretty sure the new ones are 31, since Moser makes 31 spline axles for the 2005 mustang gT, I'm assuming they would have to match stockers.

 

ALmost 100% sure its 31

 

Sweet! That's good to know... It looks like Ford Racing has been selling a 8.8" 31-spline Traction-Lok with carbon fiber clutches for a few years ($299.99) and this is probably the same unit being used in the S197 GTs.

 

That unit is junk get a Detroit Tru-trac

 

I wasn't going to post this seeing how many S197 owners have trueTracs (and w/o a doubt, the 3 pinion units), but my experience with Tractech left a bad taste in my car and I won't be giving them my business in the future. I bought a 2 pinion TrueTrac for my 00 Crown Vic in 2003 and I snapped 3 of the 4 side cap bolts. This was apparently a known problem at Corner Carvers since 1999 and TracTech knew about it but did not issue a general recall. Vendors continued to sell the 2 pinion 8.8" units. I called up Tractech and asked if I could pay them to fix the 2 pinion unit (larger Grade 9 bolts would have fixed the problem) but they refused to do anything (understandable, liability wise, etc...). It's now a $400 paperweight in my garage (the broken bolts are stuck inside the case and will require some machine shop work to permanently fix via larger bolts).

Bob Cosby had great results testing the 3 pinion TrueTrac when it first debuted as a prototype unit. The 3 pinion unit is Tractech's answer to the grenade we call a 2 pinion TrueTrac. But in all honesty, I won't be giving TracTech any of my money in the future. I would rather rebuild clutches than try to dig out metal pieces in the pumpkin (yes, the bolts in my Crown Vic snapped off and juggled around the ring and pinion gears like marbles in a tin can. Luckily nothing got jammed into the gears). I know I can depend on the T-lok for durability/reliability for everyday driving since the Big 3 have been using variations of the clutch limited slip differential for decades.

 

I like my Torsen diff and never heard of one wearing out or failing. Can't say how they would work for drag racing if that's what you're in to, but street/autox, open track, they are great!