Not for a truck, but been toying with the idea of changing gears in my '95 T-Bird.


I've got a differential from a Super-Coupe, which should be a drop in affair, that came with the factory Trac-Loc Limited slip and 3.55's


I'd like to go with 3.73's, but I'm considering going to a different style of Limited Slip, since I need to go through the whole thing anyway (not sure how much abuse the donor car saw before I got the center section)


I've been told Lockers and IRS often don't play well together, so I'm thinking a clutch style or gear style LS might be the best option.


It is a 8.8" rear, and IIRC, one needs to make sure the carrier is able to accept the circlips for the CV shafts.


Any thoughts on LS units that work well with IRS?

 

I don't know why a LSD can't work with IRS; lots of 2000's Cobras have them. The Ford Traction-Lock is a clutch type LSD. You can make it work more effectively by rearranging the steel and clutch plates. I'll have to look up the details, but you replace one of the steels with one of the old clutches.

If it's the same 8.8" differentials set as the stick axles, you can get many gear ratios for it, just like for the stick axles. You can get the Ford Racing version for less than $150:

http://www.americanmuscle.com/ford-373-7985v8.html?utm_content=Driveline+-+Gears|Ford+Racing&utm_campaign=79-04%20No%20Years&utm_source=Google-pla&utm_medium=Shopping&utm_term={keyword}&AMID=fo rd-373-7985v8-FPReplacementV1&T5_Var3=blue&GID=50351G87

Since you're going through the whole diff anyway, you can replace the R&P in the process.

Of course, this is assuming the diff unit in the IRS is the same as the on the stick axles. Someone else can verify or refute this.

If you want a different type of LSD, you will be replacing the complete diff unit with whatever that is; Auburn, Torsen, TruTrac...

 

A minor correction to my previous post. The link points to a 7.5" R&P set. Here is a set for the 8.8" gears:

Ford Racing 3.73 Mustang Gears M-4209-F373N (86-93 GT) - Free Shipping

Same price.

 

I did this with an 05 explorer where limited slip wasn't an option due to traction control. If you don't want to change the gears it's pretty much drop in. You will likely need to reset the backlash and I suggest the super shim kit which is cheapest on ebay. I had no issue with the irs shaft holding in the spider gears. Granted this was a 31 spline application but I don't see it being a problem with the 28 spline either.