Found the sneaky vibration. Maybe.

Dex, my mechanic, and I went from Concord to Los Gatos to look at a tankless water heater I found on Craig's List, a round trip of about 150 miles, and we had plenty of time to try and figure out where the constant light vibration was coming from.
Because it is always more fun to think Zebra! when we hear hoof-beats, we went through such things as an out of balance torque converter, ignition problem, loose junk in the bed, my poor driving and cupped tires. Turns out maybe it was something Dex missed when he took a peak underneath, without a flashlight, the center bearing of the drive shaft.
I sure hope I can get away with just replacing the bearing, because a rebuild and balance is expensive.
Crummy Toyota. Only lasted 260,000 miles.

Not a fun fix for sure. I would do the universal joints at that point if the bearing has to be changed out.