In good forum fashion I thought I'd close this one out with my solution(s).
I bought another rear differential and unfortunately it had some Arizona road dust inside when I received it, refer to photos 1 and 2. There were some rather large rocks in there. Took everything completely apart and cleaned in GM approved parts cleaning solvent. During the process of replacing all of the differential mounting bushings the axle bearing race on the large pumpkin housing just fell right out. I'm like OK, so it must have shrunk or something and the new one will press right in (wrong, keep reading). The bearing race was spinning in the housing, refer to photo 3. The outside of the race and the steel shim behind it were worn.
I bought and installed new clutch packs, new axle bearings, new axle seals, new pinion seal. I left the pinion and its bearings in place. Pinion gear and ring gear looked really good, refer to photo 4. I went with Timkin bearings which may not have been best choice (read on). The parts BOM is as follows:
- Rear axle bearings Timkin 32010X QTY 2
- Rear axle seals AC Delco 02291342 QTY 2
- Side cover seal AC Delco 3689060115 QTY 1
- Diff bushing, LH front AC Delco 3625995852 QTY 1
- Diff bushing, RH front AC Delco 3625995851 QTY 1
- Diff bushing, rear AC Delco 3625795472 QTY 1
- Differential clutch AC Delco 3619132906 QTY 2
I soaked the clutch plates in gear oil overnight and put everything back together. The factory manual says to replace all ring gear bolts, I decided NOT to. During reassembly I discovered the new wheel bearing race would NOT stay in place. I could actually install it by hand and once seated would rotate by hand. Definitely not good. My solution after many deliberations (with me, myself, and I) I decide to TIG weld the housing race seat without using any filler rod, refer to photo 5. Basically creating pools of metal with raised sides...kind of like the hammer and peen method but better. The race then pressed in with the help of the shop press.
So the next little deal was the diff shafts in the LSD, the smaller half shafts with sheared off pin heads. You can see this in my previous post above, #13. I ended up using the one good shaft from my old diff and one of the sheared shafts with the sheared head installed into the mainshaft hole, refer to #13 above.
And the next little deal? Well when I put the lid back on the input shaft was way to hard to spin by hand. The torque spec is like 30in.lbs. for it to spin and it was like 30ft.lbs. The only thing different were the Timkin axle bearings, these Getrag differentials use SKF bearings...all German crap...errrr stuff I mean. The bearing specs are pretty much identical except for this one parameter called "effective center location", or a(4), refer to drawing 1. There is about a .25mm difference between the two bearings on this one spec...pretty much everything else is identical including overall race to race shoulder width (20mm). In the end I removed the bearing race, removed the shim behind the bearing race, reinstalled a new bearing race WITHOUT the shim in place, and re-assembled the differ cover. This pressed the race to the needed distance and I then measured the clearance Clarence between the race and case with some gage blocks. At the end of the day the shim needed about .25mm shaved off...or about the same amount as the difference between these two bearings in dimension a(4), the effective center location. When I rebuild my old diff I will be using SKF axle bearings. After performing this the assembled diff was able to spin by hand and the backlash was well within factory spec.
I have about 500 miles on it as of now, this is my daily driver in the non-winter months. So far so good, no whining, no grinding, about same gas mileage, GREAT power, couple burnouts, some rear end slides (almost too much, ha ha ha).