I have to say I don't see why people make rebuilding a diff out to be such a complicated process. I have rebuilt at least 30 diffs, with the only special tools being a press to change the bearings, a dial indicator to check backlash, and the paint to check the tooth pattern. None have ever blown up, and the only one that ever made any noise was the one in the lemons car had a bit of a howl after boiling the gear oil out of it after 10 straight hours of road racing and running 130 down to 40 back to 130 again every 90 seconds. A case spreader is nice to have, especially if you are doing a bunch of them, but you can get it back together with a brass punch and a bench vise, so if you are only looking to rebuild your own diff, it is not necessary. For pinion depth, either reuse the factory shim, or measure the thickness of it so you know what size to use on the new one. Pinion depth shims are case specific, so as long as you match the shim to the case, you should be alright. If for some reason the tooth pattern is too high or too low once you get everything together, then you can take it back apart and adjust it, but unless someone has already been in there and screwed it up, or unless you are using some cheap gearset or somthing, reusing the factory shim will be alright. For the side shims, again, reusing the factory ones in the correct locations should give you a good starting point. Most of the time, you will be lucky and it will come out perfect by putting all the factory shims back in their original locations, but if it doesn't, that will show up in the backlash and tooth pattern, and you can adjust it from there. Having $2500 worth of tools is a good way to make sure that you only have to put the diff together once, but considering a new crush sleeve is about $12, and even if you have to take everything back apart it will take you a couple extra hours, you do always have the option of putting it together and seeing where you are at, and making adjustments accordingly to get it where it needs to be. If you don't feel comfortable doing it, then by all means pay someone else to do it, but if you are comfortable doing other work on your own car, then rebuilding the diff should be no exception.
Edit: Forgot to mention the torque wrench, I guess that does qualify as a special tool, even though I consider it a tool that every car enthusiast should own. As far as crushing the sleeve, chock the diff in a vice, screw in 2 driveshaft bolts, and hold the flange from turning with a prybar while tightening the pinion nut with a breaker bar.
-91 Cougar LS, coming soon, complete overhaul
with a 427" Windsor.
-90 XR7 5-speed black on black w/sunroof, MP2, coated rotors, double intercooler, 15%OD, ported heads, comp stage 1 cam, 85mm TB, 90MM LMAF, 80# injectors, and ported big valve heads
-98 Mark VIII LSC, Procharger P600b, TR3650 swap and 3.73s.
-90 SC Automatic rustbucket winter beater
-97 Tbird Sport 4.6 Nice weather daily driver
-"Your buddy Mike is INSANE!" -ClintD's dad
Last edited by MadMikeyL; 10-05-2011 at 10:37 AM.