grimed

Hey all,
Been reading through lots but can't seem to find the answer I'm looking for...
Heres the story...swapped a rebuilt g52 into my 83 dlx as the stock l52 was going out. Got the g52 from toy connection in Santa Clara, the owner told me to bring my L series transfer case and he would swap me a G series so I can do my swap. In my rush picking up the new tranny and t case I didn't notice the 6x bolts missing on the t case. I got it home, got the right bolts for it and threw it in anyway in hopes of it being fine but sure enough was leaking oil real bad out of a middle seam and has a terrible low end growing sound. Called the shop, owner tells me bring it back and swap for another one. So I pull the damn thing out, swap it for another. This one was covered in oil and grease but I cleaned it up real well, installed it, and now same low end growling sound. And oh, it leaks! This time from rear output seal and somewhere up high middle of the case.

So my question... This growling sound (that's the best way I can describe it, a real low growl) happens any speed over 10mph or so, gets louder and directly related to how much load engine is under on acceleration, and is especially bad on decelerating. Doesn't happen if I baby the throttle off the start, but if I hit the gas it starts immediately. When driving at speed, the sound goes away when I push clutch in. Any ideas? I did new oem clutch kit with trans swap, new throwout bearing, left the input bearing alone because I didn't have a puller and it looked/felt new. didn't change or resurface my flywheel...looked to be better shape that my clutch was in. Think old clutch was wearing quickly from rear main seal leak that I fixed. Also had both my driveshafts resized at a local shop so all joints are new, but could the slightly longer g series with a shortened rear driveshaft mess with the pinion angle that much?

I know that I haven't exactly gotten t cases from the most reputable source, but I was told that unless someone opens them up the t cases for these things really don't go bad that often. How likely is it I've gotten two shot t cases in a row?

Thanks guys