1985 Ram 50 Diesel belt issue

Can anyone serve up a possible reason for the alternator belt constantly becoming loose. I am getting squeeking and they are the proper belts finally. Very frustrating! After only ten miles the horrible squeeking begins and sure enough when I turn it off the damn belt is loose again. My mechanics I have are good ones, and they are stumped. I am too! Anyone know how to get this alternator belt to stay tight! I know it gets adjusted at the alternator but how do we keep it tight?? Thanks

Manliness and locktite.

I had the same problem only with my power steering pump belt, I ended up getting just a slightly smallter belt, and put a lock nut on it. Never got loose again. I'd recommend having someone push down on the alternator to put tension on the belt while you tighten it, make sure you get both bolts tight, I believe the alternator is the same on all models of 85 and 86. Hope it helps. Just don't go too tight.