i didn't mention it before because this is a Mopar board, and this car is a 58 impala custom.
a while back, i asked about this on the general forum, and didn't get much response. [although i did get a couple of ideas. THANKS to those guys !]
so i figured i might get some ideas here, since handling is appropriate to everything.

i don't want to run afoul of any rules, but this thing is taxing our minds.

it HAS to be SOMETHING causing this symptom, but we haven't been able to pin point the cause.
this is a very nice car, and not a slopped/slammed together p.o.s.
previously, this car had air bags, but those proved problematic with the controls, so that setup was removed and the factory springs/arms/bushings setup re-installed.
the car also had this problem with the bag setup, everything is new now, so the only thing left from the bag setup is the 500 box, the pump/pulley arrangement, and the steering column/ shaft hookup to the box.
the car had the factory manual steering box with the bags, and we converted it to the 500 series power box at that time because it was hard to steer with a 14" diameter wheel.
however, with the manual box, it DID go down the road without having to correct the input all the time. we do not know what the alignment specs were at that time [with the manual box]

since the power box conversion, we have had this car on the alignment rack twice, and it does the same thing.
i will attach the last printout from the rack. maybe something can be seen we are missing.

there has been NO hacking or butchering done to the chassis, and from all our measuring, the chassis is factory straight.