I had it checked out by our excellent mechanic and they are pretty sure it is the accumulator for the hydraulic suspension system. that would explain a few other things such as the really rough ride over mild bumps. the trailing arms and supports are all fine.

the noise at high speeds after a bit of driving is most likely coming from the dust guard over the brake assembly coming into contact with the wheel rim. i looked at it when the car was cool and there wasn't much space between the guard and the rim on the slanting side.

they'll replace the accumulators on both sides to correct the suspension problem and hopefully that will take care of the cockeyed wheel.

just cracked 300,000 miles...