I have a 1996 F-150 XLT 4×4 with a 5.0L V8 with just over 80K miles on it. I take very good care of it, I had the drive belt replaced about 10K miles ago and for some reason this morning when i started it up it started to squeel. I turned on the a/c and it quited down, then when i turned it off it started again. It squeeled the entire 8 miles to work threwout the RPM range. It doesnt have any tears or rips in the belt. What do you think it is? How often should the drive belt be replaced? Do you think its the a/c compressor?