Hi guys. My brother has a 2000 SIlverado 2500, its the non-HD 2500 with a 6.0l gas engine. The transfer case is an NP246 with autotrac. He noticed a bad clicking/popping soundin 4wheel drive the other day, which I mistakenly thought was a bad CV joint. The noise is very much like a bad u-joint/CV joint. After that didn't fix it, I took a look at the transfer case and found it completely dry. I filled it up with fresh ATF (I know the Autotrac takes a special fluid, but its gotta be better than none at all) but the noise persisted and is definitely coming from the case. So I think running it dry damaged the clutches and maybe more. Actually, I suspect this is a victim of pump-rub although I can't find the hole. The case had blown all the fluid out back out by the next day.
There isn't a whole lot of money to throw at this, so we've decided to source a used transfer case and be done with it. Just need the truck to last one more year before it's put out to pasture. The main question I'm asking is are all NP246 Autotrac cases created equal? I found one for cheap but its out of a 2000 1500. I'm not sure if my brother's truck has a 4L60 or 4L80 trans, but I can find out.
Thanks for y'all's help!

Dave