In the past month or two I have noticed a click/clunk noise when I get off the throttle. It sounds like it is coming from the rear end and or transfer case. At first I thought it was due to the fact that I lost all the grease in the rear slip yoke from a broken zerk. But after replacing that and lubing back up, still the same. So crawled under the rig again to check the u-joints etc and I can duplicate what I 'think' is the noise I am hearing inside the cab by rotating the play in the drive shaft to where it causes the gears in the rear end to hook up. Checked the rear end fluid and that is full and clean. Just wondered how much play is considered normal (I haven't measured but would guess mine has maybe 1/2" of rotational play). So if I am under the truck and rotate the play back n forth, I get the annoying clunk that I am hearing from the rear end. Is there a way to get the play out and make it tight? I'm totally shooting in the dark here so please inform/educate me. I DON'T want to take it to the stealer for fear they will tell me my gears need replacing or something to that effect.

thanks in advance!