I just had my Yukon V6 4:88's installed with a '91 Supra Turbo LSD carrier. Wow, what a difference. No more "bogging" on takeoff, and it climbs hills like a normal vehicle, I even got up to 80 (corrected) briefly to see what the RPM's were: 3500 RPM. I had my wife pace me, and my speedo is now 5 MPH off, on the high side. The mechanic is an 80 year old gentlemen who specializes in diff repairs, so he enjoyed the challenge of getting the LSD carrier to fit and work right. He said he had to change the pinion shim from .074" to .030" to get the contact pattern correct. He also said he had to grind 1/8" off the axle on one side, and 1/4" on the other side to work with the LSD carrier.

I wonder if I could get a new transmission speedo gear to compensate for the gear change?

In the next couple weeks I'll pull the front diff and get it done, so for now no 4WD. I don't know if it's been tried yet, but I have a rear diff from an '84 Supra that's 7.5", 2-pinion LSD. So, I'm going to pull the carrier out, and see if the guy can get it to work in the front diff. If not, only $25 lost, no biggie.

Cost (I got the gears about a year ago, so I don't remember exactly)
about $250 for the gears and install kit from Randy's
$150 for the Supra Diff from eBay
$300 for labor (It took him 1.5 days to get it done)