OK so sometimes as I'm driving along at a higher speed I will suddenly get a real noticable vibration in the rear of my '94 XJ. It's bad enough you can actually hear it like a low hum. But all I need to do is take my foor off the gas for even 2 seconds and it goes away and won't come back when I re-apply the gas. Since it goes away so quickly just from taking my foot off the gas so briefly does that tell anyone what it most likely is? Thanks in advance.

 

title made me lol sick mind and what not

 

lift?
check rear drive line?
sye?
balance tires?

 

Mine did the same thing after I installed my lift kit. I lowered the transfer case, and it went away... Sounds like a driveline angle problem...

Or possibly a U joint or pinion bearing??

 

with stock suspension it sound like you rear u-joints may be going out or possibly pinion bearings