[Fred n' Ethel]

OK, looks like we were all right.
It was an evil combination of the loose kingpin and the eggy wheel being on the same (right) side.
Swapped right tire w/left and all tests up to 70 mph were acceptable .... till I get a matched pair of new tires.
All in this regard is goo, thanks.
Now ... another issue.
When I bought the truck, the PO said the brakes will lock up on the first application after sitting a while. Well, it did it on the initial test drive, but never does it again till it sits a while.
While I was doing this tire diagnostic, I pulled all the wj\heels and drums and looked it over.
Front left was missing the the nail looking pin that comes through the backing plate that holds the shoe against the plate. The spring clip was still in there though and just tumbling along for the ride. I assumed I'd found the problem with this missing pin thinking the clip was jamming that one shoe/wheel cylinder and applying pressure to the other 3 causing the jamming, made a new one and tried it out.
SAME dang thing happened. After a a few firm apps of the pedal, it smoothed out and worked fine (perfect, actually) for the rest of the outing ... 40 or so miles with many stops along the way. Anxious to see what happens the next time out.
What the heck would make them jam up and lock like that ?
All the shoes were clean and dry with plenty of meat on em', the drums look
good and were dry except for the rear left that had a little oil from a leaking axle seal. It looks/acts like they ALL lock up though .... not just one. It's like a blast of hydraulic pressure is being applied to all .... but not from my foot.
Any ideas ?
Thanks again Gents.