I have a 98 two door cherokee and every time I go to accelerate from a complete stop I hear a clunk I'm not sure what this could be it sounds like its coming from the rear

Start with looking at the tranny mount and ujoints

What gear ratio and trans do you have?

Just did front u joints never touched the drive shaft ones i will check tomorrow at work an get back to you also how can u check the trans mount

Stock gears and stock trans I'm not sure what gears are stock for a 98 2 door sport

Tranny mount and u joints are all fine

So the clunking comes and goes I'm not sure what this could be any suggestions what to check next it sounds like it could be in the rear

craw underneath and try turning the drive shaft and see how much play is in it.

I know you say it sounds like its coming from the rear but this really sounds like your engine mounts are bad. Check both. This can let your engine rotate violently under torque and shock load your driveline, t case, ect.

pull your rear drive shaft and grease the slip yoke. A lot of people use anti-sieze.

I had/have the same problem. I replaced the ujoint on the rear driveshaft and it got rid of the clunk while switching gears but I still have the low clunk when accelerating from zero or letting off the gas then accelerating again. How would you check the engine mounts?

Easiest way would be grab a friend you aren't too fond of (in case he gets ran over), pop the hood, start the jeep. Put on the e brake as tight as you can and hold your foot down on the brake pedal. Shift the transmission from neutral to drive, neutral to drive. Have your buddy watch (from the side of the rig) and see if the drivers side of the engine lifts up and rotates. If you dont see any movement you can lean on the gas a little bit but be careful. This seems to be the quickest and most effective.

Have you checked your u bolts? Are they torqued to spec? Maybe your axle is rotating under the leaf pack.

Im gonna check this when I get home. I'll let ya know what happens. Would the fact the my leafs are so flat there almost inversely flexed be a problem?

From what I have seen and heard, stock xj leaf springs (at least 97-01) are flat from the factory. Mine were flat before I added a leaf and after measuring I found out they hadn't sagged at all. Stock measurements from center of hub to bottom of flare is 17.5" front 17" rear.