l replaced the two belts on my 90 TC (Ford 5.0L)... The belts are tight and the belts are correctly aligned... however, l have two issues:

1) My engine revs MUCH louder now... this is not much of an issue, and it is only loud if l depress the pedal more than half way... but it sounds like l have a new exhaust on there. Kind of weird.

2) The fan belts slip (and squeak) if l floor it all the way. When l floor it, first gear should max out around 40 or 41mph... however the belts start slipping around 36 mph and it upshifts around 38 or 39mph.

The belts could be slipping earlier and l might not be able to hear them squeak due to the engine being louder.

Unfortunately, when l put the belts on, l did not know if l was supposed to ''resurface'' the pulleys like you do with serpentine belts.

Any ideas?
Could too tight belts cause this? If so, should not it resolve it self since new belts ''stretch'' after a while?
After driving it a bit more l think it is coincidence and that the transmission is actually slipping at high rpm. =

you have something wrong maybe the belts are to tight or you have a bad pulley

l have no idea, I'd replace the pulleys with serpentine belt pulleys. That is not too hard of a task. l hate V belts.