Shredding belts.

You said you went through 3 belts in 100 miles. Unless you're constantly driving around with the steering cranked all the way in one direction, it's unlikely that this is the problem. A worn drive pulley that's constantly slipping will kill a belt in just a few minutes. When the pulley gets glazed and overheated, it kills the belt even faster. I still suspect the pulleys are worn out.