Remove the serp. belt. Spin belt tensioner pulley, does bearing feel okay?
Does tensioner the tensioner fight you and have a healthy spring when you remove the belt?
Spin a/c pulley, any rough bearing noise or growl?
We want to elim. belt slippage as being a prob. , then isolate the noise.
While the belt is off spin water pump, alt. and fan (fan mount bearing), these should also spin freely and not have bearing growl or noise.
Inspect face of a/c clutch are the "spring" fingers broken? if so the clutch likely will still work but should be very noisy and may not engage/disengage properly.
BTW, the clutch for the 94-95 model should fit the later trucks, but you'll have to swap your clutch wire elec. connector over onto the new clutch coil wires.
Special tools are necessary to do this properly and you may find it easier to recover the refrig. and then remove the compressor and do this on a work bench.
A trustworthy a/c shop in your area, may likely save you money in the long haul. .
Good luck
Andy