md21722

Vibrations in the front floorboards by your feet usually do not have anything to do with the rear axle.

1976gmc20

I'm not an XJpert, but a lot of questions on this forum are just basic mechanical stuff. I'm just guessing that the torque load eases off at higher mph so therefore the vibration mostly ceases.

investinwaffles

IDK,
It sounds like you have replaced a fair amount thus far. Honestly, changing out the rear bearings is pretty darn easy.

I would save up for a rear disc conversion and do them at the same time. Bearings are only $12 for Timken OEM quality ones;
http://www.rockauto.com/catalog/more...nid=454&jpid=4

With 200K+ miles on the clock I cant imaging the original ones are in great shape anyways.

Nottingham15

Have you looked at your rear brake drums?
I recently had a vibration that I could pinpoint to the rear left whenever I accelerated from stationary. I took the drums apart and it was obvious the whole mechanism needed replacing.
As I knew it would take a week to get the parts I cleaned and reassembled the brakes to keep the Jeep on the road.
The vibration has gone. I think it was the shoes vibrating on the drum, having not retracted properly.