Here is a picture of my AC compressor viewed from the bedroom access.
Note the silver bolt sticking up in the top of the picture.
Look directly below the bolt but into the engine compartment.
The compressor is attached to the engine and is driven by a dedicated belt (which you cannot see).
The compressor looks just like the one on your cars or trucks but is a bit larger.
The model number info is on a label either on the back or side of the the compressor.
It is relatively easy to work on with a side mount radiator like my DP has. On your gas rig you should be able to see it by standing in front of the engine compartment.
I bought the gauges, vacuum pump, parts and new compressor and replaced it last summer. Nice cold air this summer from the front and rear, engine driven AC system.
BUT....... I also learned what others are saying. There is a lot of pressure remaining in the system, if a part is removed in the wrong step or via failure, the dislocated part could penetrate your skull just like a bullet.
BE CAREFULL when messing around in there. I ... got ... lucky....