So a couple weeks ago I finally got tired of hearing my rear end howling like a coyote so pulled my IRS to rebuild my rear diff and replace the IRS bushings. Didn't have the scratch at this time for Bruce's kit so just went with MM urethane. Still a marked improvement over stock. As for the rear diff I installed all new bearings and seals, new carbon fiber trac-loc from Tousley and FRPP 3.73 gears and Billetflow IRS brace. I made a custom holding fixture that I lagged bolted to my bench. The rig was made up of 1" square tubing and allowed the diff to hang down off my workbench. I then made two adaptor plates using 4" wide and 1/8" thick strap steel. I drilled two 7/16" holes 3.2" on center apart and 1/2" away from the edge. This allowed the plates to be bolted to the diffential case edge yet stay out of the way. I drilled two 1/2" holes centered in the other edge of the plate. The inner hole is to secure the differential to the holding fixture for torquing down carriers bolts and pinion nut. The outer hole is to attach my homemade case spreader. Here is a shot of the diff housing mounted with the plates in the fixture (in bolt torqueing mode). I made the spreader using 1" square tubing for the sides and 3/4" square for the top and bottom. The 3/4" fits inside the 1" nicely so I was able to notch out the ends of the 1" to accomodate the 3/4". I attached the corners using 7/16" clevis pins. I then drilled 1/2" holes in the middle of the sides. These holes have 1/2" clevis pins that insert into the outer holes of the holding plates. I fasioned the adjusting bolt using Racebronco's design. With spreader attached. When using the spreader the diff must float in the fixture. Notice no pins holding the diff to the frame here. Nevermind the c-clamp ;-) Because I was installing FRPP 3.73 gears I started with the stock pinion shim. I had to fool with the carrier shims back and forth for a while but finally got it dialed in with .011" backlash. Nice! A little shim makes a huge difference to BL! Don't have a picture but ran some marking grease on the gears and the pattern looked great. I got lucky on not having to fiddle with the pinion shim. I used a long piece of flat stock attached to the pinion flang that was just long enough to stop itself on the wall stud behind the workbench. This allowed me to torque the pinion nut with a breaker bar instead of a impact. It doesn't take much at all to go past the 29 inch pounds max of pre-load. My first attempt I was at 10In-lbs. Gave the nut maybe 3 degree's extra turn and the torque was then well over 30inches. I took it apart again and used a new crush sleeve and this time stopped at 20inch pounds. I also replaced my side bearings and seals. This set of tools from Harbor Freight is probably one of the best bang for the buck tools I have purchased from them. Makes race and seal installs a breeze. Pilot bearings too! My new gears are nice and quiet now and no more clunking from the rear as I replaced all diff and irs bushings and also replaced the front bolts with the 14MM ones. Before I started, my pinion had lost it's preload so had some obvious play back and forth and of course 0 preload torque. The ring gear had .018" of backlash which is really only .003 over max spec but my god the noise it made! I was expecting to find a ton of shavings when I opened the rear cover but everything actually looked really good. The only damage I found was some pitting on the main pinion bearing.