I have two diesel K5s, an '83 and an '86 - not that the diesel makes any difference with this problem. I burn up rear u-joints all the time. My’87 Suburban, with the same joint, gets over 100K on the rear -joint (longer wheelbase - less angle). I've tried the usual attempts to remedy including various u-joint brands and grease, lowering the transfer case to make the angle less severe, bleeding the newly installed u-joint of air when first greasing, etc. etc. Lowering the transfer case by relocating the factory bushings required lowers the [censored]-linkage bracket. It didn't make the joint last any longer, though. I also had one bad episode with NAPA. They had some u-joint retainer straps that were a few thousandths too big. My driveshaft flew off and blew my transfer case to pieces. The most alarming thing to me is these joints go with little warning, i.e. they don't start making noise gradually or vibrate. I had one occasion where I just came home from a 200 mile trip at 75 m.p.h. speeds - all very smooth. Parked in my driveway for minute, then tried to back out - and my driveshaft fell right off. The joint goes bad, wobbles a bid, gets loose in the straps, and the caps fall off. Seem, if it could be converted to a u-bolt retaining system, with a drive-flange with ears (that prevent cap fly-way) things would be much better. Some K5 Blazers with standard shift have this setup. Has anyone tried changing the angle of the rear-axle, i.e bringing the drive-flange up and thus reducing the driveline angle? It appears this would do more than lowering the transfer case. I have an '86 S10 Blazer and I've gotten over 100K from the rear u-joint - and the angles are very slight.