My husband has a '88 Ford F-350, its a 5.8, with a 351. There is lots of squeaking going on. After taking it in to a few places with no luck of fixing the issue he has decided to tackle this project himself. We replaced the alternator...still squeaking. Replaced multiple belts...still squeaking. Most recently he replaced the water pump...STILL SQUEAKING! We think it may be the water pump pulley. Now, here is the issue, NO ONE CARRIES THE WATER PUMP PULLEY! Anyone know where I might have luck finding one?

Thanks!

 

You can easily confirm if the noise is coming from belt/pulley by just spraying a little water on the belt. If it goes away we go from there. You don't mention if anyone replaced the belt. I wouldn't suggest belt dressing because all that does is make a mess.
A good part of the time belt noise can be caused by misalignment of the pulleys, but a dry belt can do it too. A few drops of brake fluid have provided a longer lasting solution to dry belt noise and might help. As far as the pulley, they are possibly the same for several years and a salvage yard (junk yard) may have a few available. Don't remember if an idler /tensioner pulley is used , if so that could be the culprit.