Normally a bent wheel or tire out of balance.
I was told by a buddy of mine who's a GM Master Tech that it's the Universal Joint in the axle. He said I'm better off just replacing the axle with a reman for a few dollars more.
shake
shake
shake
A worn out Universal joint in the rear driveshaft.
Worn steering parts, worn suspension parts, tires out of balance, out of alignment,
Low pressure in the tires can cause shaking, the alignment can cause shaking also.
rattle
to quiver or shake a lot and to vibrate
pencils vibrate when someone moves it or shakes it.pencils also vibrate when there's an earthquake.
You shake it till you make it!
to quiver or shake a lot and to vibrate