can i drive the truck when i need the a/c compressor replaced - i originally took it in to the shop because of the rattling under the hood - now with a/c off the rattling is less

 

You can,but if the compressor locks up,you will loose the belt.My suggestion is to either get the compressor replaced,or purchase a belt for your vehicle without A/C.
Needless to say,getting the other belt is WAY cheaper.I have a compressor in my attic for a 97 that has no clutch if your interested.Dont have the 97 any longer,and its just collecting dust.

 

You may need only the pulley or the hub, not a whole compressor.