Really weird front end clunk (was embarrasing 4k sway bar Q)

[Dwight & Tina Varnes]

Continuing with the diagnosis, I've determined my problem is NOT the
sway bar mounting. It only hits the strut bottoms when the car is topped
out, i.e. up on jack stands. Plenty of clearance on the ground.

Symptoms (and read them all and think first; it's not the obvious
answer):
1) Thunk or pop during hard left turns, like parking
2) Steering wheel straight, then will 'pop' and be off center while
going straight   (after a turn, usually a left). Tracks basically ok
with only a slight pull off center. Squirrely, unpredictable cornering
during left turns.
3) With the wheel turned hard left and pushing the car slowly, I can see
the RF wheel 'pop' along with the thunk sound.
4) This is the good one...reverse is intermittently a problem. Depending
on the position of whatever is causing the problem, reverse will work
either perfectly or pop out of gear every time and be impossible to hold
in!
The problem is concentrated on the right side. It appears (but may not
be) it is related to the hub/axle/bearing/transmission more than the
steering or strut action.
This all started very suddenly after driving carefully on a gravel road.
Nothing was impacted.
Tie rods ok, steering rack firmly mounted and ok. No noise from wheel
bearing or cv joints. All bushings are new or reasonably new. Ball
joints, A-arms, subframe mounts, etc. all appear fine and are not
moving.
This is baffling to say the least. My only ideas are:
1) wheel bearing (should make noise, or have made noise previously)
2) CV joint or axle (where is the clicking sound?)
3) transmission (worked fine before, and why would it be related to the
wheel angle?)
4) ???
Ludicrous suggestions welcomed.

Dwight Varnes
86 Coupe GT