My 93 FLSTC with 25,000 miles has developed a squeaking sound when I let off the gas. Sounds kind of like my kids hamster wheel. Any ideas what it could be?

 

I would guess your drive belt is making the noise. If so, check it for correct adjustment, I would check it and the pulleys for abnormal wear. If all is good, clean it. This always took care of the belt squeek on my bikes. I would think there is a belt dressing available for severe cases.