If it's an SLT model, the wiring is all there. just need to get a mirror adjustment knob (ebay) and if its heated you will need the climate controls with the mirror heat button. (ebay) then its all plug & play.

Mines a 2001 SLT so you saying that the wires are all there? I dont need heat here in the south... but not wireing is a big up for me... are that fused in too?

Yes, that's what I'm saying. the trucks with the SLT package all have the same wiring harness regardless of the options ordered. If it is an SLT there is a plug inside the door to plug the mirror control into. and if you dont need heat then you wont need to get the upgraded HVAC control. It is an easy swap. I did mine in a hotel parking lot with a screw driver and a 10mm wrench. was a piece of cake.
the only thing is that if you are upgrading from regular mirrors to towing mirrors there is a "support bracket" that helps hold the extra weight of the towing mirrors. this bracket is only avail from the dealership (so i have been told. but it is cheap) if you are upgrading from manual towing mirrors to power or power/heated towing mirrors the bracket is already there. and yes, you will probably need to use the longer threaded studs from your old mirrors I forgot about that part. (thanks Chadcycle 2500) and be careful how you route the wires from the mirror. there is only one correct way (mine came with a diagram ) if you route them wrong you will pinch and cut the wires when you tighten the mirror bolts.

Tow Mirrors
 

I'm all over this idea thanks a ton!!!!!!