So this just started today but when i take off somtimes not all the time but from a complete stop as i get going to back end shakes and you can hear it shake the jeep. i have a 1989 xj two door, inline 6.... typical stock jeep, she has around 209k, last week i had some dw and i snugged my trac bar witch was and easy fix but now it is this and it is the back end and i have no clue what this could be also when i let off the gas and that push it back down it goes away???

 

Possibly a bad u joint in the DS, bad wheel bearing, bad springs/bushings... Could be as simple as needing a new balance/rotation. Is it guaranteed rear end vibes, or is it possible it's somewhere else?

 

Rear trans mount bad or missing bolts?

Time to crawl under the Jeep and start gandering and wiggling.

 

Sometimes I think a bad drive-line U-joint vibrates a little like haven a "fish 0n". Not buzzing like an engine, or WOP WOP like wobble or out of balance. (maybe a little "wop", going slow)

You gotta have the drive-line "loose". Withe the rear wheels chucked, in neutral, see if there is any play at all. "zero"is the spec, no play! (when you wiggle and rotate it)