I hear a clunk when reversing direction. I figured there must be play somewhere between the transmission and rear wheels. Most points seem tight - u-joints, driveshaft bearing, transmission tailshaft - but with one rear wheel in the air and the transmission in park, I get some wheel rotation. I thought there should be none, but an old post suggested "locking the back wheels and then turning the input flange. About 1/8 turn is normal, 1/4 is getting worn." I'm sure mine is no worse that 1/8 turn, so I guess it's fine.

Some have suggested that it's the bushings, and indeed my trailing arm bushings are shot, so maybe it is the axle casing shifting as torque is supplied. In a final check, I put both rear wheels in the air and rotated one wheel from a forward to a backward rotation quickly. This caused the differential pinion flange to jump up and down, so I think this confirms the bushing issue. While both wheels were in the air, I spun them, and I hear a clicking/ticking sound consistently about every 1/4 rotation. It's the same on both sides. The bearings generally seem a bit noisy, but it's this click that surprises me. I don't think it's the brakes, or it wouldn't click so consistently. I checked the diff fluid level for the first time ever, and it was good, so I don't think it has a problem.

Are there more definitive tests to determine if the rear wheel bearings are worn? With the attached shaft, I don't think it's as easy to torque the wheel top/bottom and front/back as with the front wheels.

Some posts have suggested that a re-packing of the rear wheel bearings is all that is required. This doesn't seem too difficult, but a bearing replacement might be beyond my capabilities, with the need to cut off the retaining ring and press the bearings.

I'm wondering with the need for trailing arm bushing replacement also, if I should think about a completeh rear axle replacement from a wrecker, or if I'll just get more unknown status components by doing this.