I have a 1995 Legacy wagon with what feels like a sticking somewhere along the drivetrain that produces a very loud clunk when it "lets go". This only happens after engaging in reverse gear. It doesn't happen right away, but rather when enough strain has been generated on the drivetrain. i.e. backing up uphill, or once throttle is applied in reverse. It does not happen with the FWD fuse in place. I found that out when diagnosing a different issue, which has since been resolved. I checked all suspension mounting nuts/bolts for proper torque specs when replacing the rear crossmember (it wouldn't pass inspection due some rust spots). And afterwards took the car in for a second inspection. The shop looked over everything including bushings and mounts. The problem was present before the swap, however.
All fluids including the front transfer case, tranny, and rear diff are no more than 6 months old. There is no binding even with the steering wheel in the lock to lock positions.
I doubt it has anything to do with the struts as most of the searches having to do with clunking point me to since the problem goes away when AWD is disengaged.
Any ideas as to what else to look for would be appreciated.
Jim