This 1991 Isuzu pickup is a rarity in our fleet simply because it isn't a Ford or Chevy. I don't know how many we had back in the day. But only two remain that I am aware of. This one arrived at the shop for its regular maintenance service as well as a belt squeal concern.

I found the alternator belt quite loose, which explained the noise. The problem was I discovered one of the alternator bolts missing, meaning the alternator was being held in place by only one bolt, (the bolt holes can be seen in the photos above and below).

I was able to find a metric thread bolt that was long enough. With an additional bolt holding the alternator in place, the belt would actually stay tight now.