Drivetrain Issues

[Mizz]

I have a 92 gmc sierra 1500 z71. Lately it has been giving my trouble while trying to drive it. ONLY under any kind of acceleration it will clank very loud, and while it does it, it feels like the gears or something are locking but only for a split second. It is getting bad, normally when it does it, the truck will clank very loud and seem like something is hanging up, wanting to stop the truck for that split second. After it does this for a while (anywhere between 50feet to several miles) the transfer case will pop in to neutral. It seems to me like the transfer case linkage is out of adjustment because if I get it in just the right spot (2hi) it won't do it for a while. I don't think its the front driveshaft yoke, it does have some slack but its not that bad. I just replaced the rear u-joint. That didn't have any effect on it. I'm thinking its either a transfer case issue or maybe the gears are going bad? any help would be great, thanks in advance.

[xtreme77mopar]

does this tend to happens more when going around corners at a slow speed?