Another Clunk Thread

I have a 2002 Silverado 4.8L Automatic

I know there are alot of threads out there about the rear end "clunk" I have read them all and everyone seams to describe a certain clunk. Maybe im not reading them right, but my sound i think is a little different. My clunk only seems to happen when i think the trans. shifts from 1-2, or 2-3, one of the two shift point, and then i can hear a slight clunk in the rear, not all the time, and not everytime, it almost seems like to me like the there is a split second lag in the shift, and when it kicks into gear, it grabs a hold of the everything and starts turning. This might be the same problem. But to me it seems a little different. Also if im going to change my rearend fluid, what weight and type should i look for.

I used Amsoil synthetic 75W-90 Severe Gear lube. I also used a bottle of slip lock additive for my anti slip rear end. The amount of lube needed depends on the gear ratio.

I had a problem with my 2000 ext cab 4x4 and I changed the lube out of the transfer case with what they put in them now from the factory and it's quiet.

You changed the fluid in the transfer case or the rear diff. case? And what do they put in the rear ends now from the factory?

A changed it all but the transfer case was what was clunking....if I can find my old post about this which had the name of the lube in it I'll post it again.

Ok, i have the 3.73 gears, does my problem sound like something different that the clunk that everyone talks about? Also the transfer case calls for Auto-Trak II fluid. Do they make a equivalant or something that i can pick up at the parts store? And so how much fluid would i need for the rearend then, i know they say to only fill it up so far from the check plug, so how do you really know how far you are from the hole?

Auto-Trak II fluid...that's it...that's the one....get it from the dealer nothing else will stop the clunk.

Ok, changed transfer case fluid last night and rear end lube, transfer case already had blue fluid in it, and rear end lube actually still looked good, and so did the transfer case fluid, still have that tiny clunk while it shifts in between gears every now and then, i almost think i need to change the transmission fluid and filter. I also grabbed a hold of the driveshaft while i was under there and twisted it to check for play and there is not play, just a little twisting movement like you would see on any car. I dont think my clunk is the same problem that most everyone elses clunk is.