I jacked it up to see why it's got a death wobble.
Looking in there, I guess I need new bump stops and shocks, but the brakes were actually great, to my surprise. Would have imagined they'd be warped or worn, but not so. In fact the hub bolt is so rusted-on, it's probably all original under there, except the shocks.
And I found out what's causing the death wobble:
That, and the wheel looks like someone took an angle grinder willy-nilly to the back of it, and the edge of the tread is starting to disintegrate. Faulty tire mounted on a damaged rim. If only I hadn't deleted the PO's phone number. I suppose, with some searching, I could find it, but I'm pursuing this. That tire's barely a month and a half old, it shouldn't be coming un****ed so quick.