Where can I find the altnertanor

The alternator is one of the belt-driven accessories on the front of the engine. It should have a wiring connection coming out of it and will be either on the upper left or right hand side, front of the engine on a 305 in the Caprice.

Littlehorn is correct I don't know what year your car is but it is probably on the passenger side upper left side of the motor. It should have a red wire bolted to the back of it and 2 wires that plug in on the side. For a diagram you should into a HAYNES or CHILTON book from a parts store or the library may have them.

a diagram? now that you know where it is ,what are you going to do?

If you do remove the alternator to have it bench tested or whatever, don't forget to disconnect the battery first! You seem new at this, but an alternator swap is a easy thing for most people doing car repairs for the first time. Get factory manuals for the car if you can find them.