Too much slack in the drivetrain?

[Krawler00]

I pulled off my rear drums to inspect a noise this weekend and could find nothing wrong. Still have a slight roar and slight clicking noise while slowing down not when using brakes and roar while driving but not sure as to what it is. Well, while I had both tires off I put the Jeep in gear and let it run hoping to find the noise. No go. I did however find the source of my clunking. It seems to be coming from the trans case or trans. I can put my foot on the gas and hear a clunk coming from the area. When I let off the gas it acts like it has too much slack in the driveline... kind of backlashes a bit too much. Like when you have it in 4low and it backlashes while 4 wheelin. Can this be adjusted? Not sure how but I know it's somewhere in the trans or transfer case. I looked at the chain while doing the sye and it looked good, no big sags or anything. I was shown a set of teeth that looked a little worn on one of the drive gears in the trans case. I was asked if I stop fully before putting it into 4low. I was told it looked like normal wear. Any suggestions or clues???? ???