Hey everyone, i've been traveling for work most of winter and i barely got to use my jeep. I came to start it last week and it didn't start the battery was dead. I put another battery in and it started up fine. I let it warm up, and when i put it in drive it started to make a weird cracking noise coming from the transmission area. the noise only happen when the engine is under load, and it gets quieter as the car gets to 30+mph...

I searched around and read about loose flex plates, but it seems as if loose flex plates make a knocking/cracking sound sound even when in neutral.
when i put my jeep in neutral and rev it i don't hear any weird sounds. any thoughts?

Check clearance between the crossmember and exhaust pipe. Load will bring it closer and make it rattle sometimes. That's why you only hear it under load. Eventually it will get bad. Enough to where it's doing it all the time. Should be a thumb sized gap between the crossmember and exhaust. If there's not that much you could have a bad trans mount

^^^x2

I would also look at your engine mounts to they might be worn and causing it to rub. If the jeep sat all winter I would also look at the U-joints as well just for good measure.

Just took a look under there, and u-joints are nice and tight. nothing looks out of the ordinary other than some oil on t-case but thats been there forever.
drove it about 5 miles today and the cracking sounded like something was loose/slapping around in the tranny or t-case. it only happens when in gear around 1500 rpm. i can rev it all i want in neutral and nothing happens.

Cracked flex plate?

It almost sounds exactly like a cracked flex plate but it doesnt do that sound in neutral. in my experience you can hear a cracked flexplate anytime the motor is running.

Is it something you might catch on a U-Tube vid?

No i have had a number of these jeeps only do it under load. I replaced several back in 99 when i was still working at the local Jeep Dealer.

I bet it's a drive shaft U-joint.

ok so i just had time to get under it again with the intensions of removing the inspection cover and making sure my flex plate was not cracked and the bolts were all tight, i get under there, and find out i don't have the inspection cover installed.... the flex plate looks fine and all the bolts are good... do you guys have any suggestions ?i'm sure its the flex plate, the sound is like every flex plate issue i've heard about.