Quick non-mopar question...

Neighbor of mine has an 03 GMC Envoy XL 4WD that's in the shop. Supposedly he "blew out" his transfer case and both front and rear differentials. Is it common to lose the transfer case and both differentials at the exact same time, or is the shop blowing smoke up his ***? The shop wants $2k to fix it, but he doesn't have it so is just planning to sell the truck to the junkyard. I'm trying to see if a friend of mine, who owns a different shop, would be interested in buying it from my neighbor to fix and sell, and maybe get my neighbor a little more than the $125 the scrapyard will pay him for it.

Anybody have any experience with this? I've never had a 4WD vehicle, so I'm really no help in that area. Thanks in advance.