Howdy! So guess what? All that money for front U-joints and a rebuilt front driveshaft and my vibration is back again from 60-80mph! Upon doing more research, could it be the rear differential gears?

reference this thread: https://www.cherokeeforum.com/showth...ight=vibration

Here's my rundown on the car since I got it:

I've had the Jeep for about 70,000 miles and the differential fluids have never been changed Excuse: the mechanic said that there are little metal pieces in the oil that if I changed the oil out then I'd get problems!

I've never flushed the radiator (it still runs cool and I've replaced the water pump...would they have put new fluid in there when they did that?)

Oil is changed regularly, no problems there.

Transfer case is a rebuild from a few years ago, but fluid has not been changed since.

Transmission has not been flushed since I got her either, so 70,000 miles too.

Power steering pump was replaced a few years ago: I assume fluid would have been changed with it. But it has not been done for a few years. The steering is really loose though, (ie: I can be driving straight and wobble the wheel back and forth and the car doesn't react!!) *getting alignment today

Brake lines have never been flushed since I got the car, but it did get new rotors long ago and I changed the pads last weekend.

I don't remember the last time I did a tune-up for new distributor cap & rotor, wires and plugs.

Obviously then, the latest is to rebuild the front drive shaft and get new aftermarket heavy duty U-joints.

So I guess the whole point of my really long post is to ask what I should be doing in order of importance (after I get this dang vibration fixed!).
My brother just bought another car and the Jeep is finally MINE!! So I want to bring her back to 100% or at least 95% before I start general mods. Thanks for all your helpful information before and that's why I come to you as a resource.

 

Sounds like you have a pretty good list to work from right there.

 

Differentials: should I change the oils? Was that mechanic right?

 

IMHO he was dead wrong. If your fluid has grindings in it it will act as an abrasive and slowly eat your gears. I would change it. Yesterday!!!