So I was driving along the highway and as I hit 70 to 80 mph, I started feeling a vibration in the car.
Seat of the pants, or side of the door touching me was vibrating different that the car normally does.
If I backed off below 70, it went away.
it wasn't continuous, and it wasn't rythmic, it just popped up every like 15 to 30 seconds.
steering wheel wasn't moving and it didn't seem like the road doing it.
driven that strech a bunch and never seen it before.

I recently changed out the u-joints, but I checked them and they seem fine.

rear wheels seem to be on tight.
I tried moving them and there is some cluncking side to side when I pull push on each side. not sure if that is normal or not.
bad bearings in the front at least make a heck of a racket.
a while back I pulled the axles to put on rear disc brakes, and I greased the bearings, but didn't change them.
not sure what else to look at.