The first thing you want to check is your taillights. If yours doesn't have separate brake/turn lamps, then you will have to use a logic circuit. I want to say the 83 does have separate lamps though, so you should be ok. Here is a wiring diagram from another thread for your year model:
http://www.73-87chevytrucks.com/tech...s_rr_light.jpg
I installed an aftermarket third brake light license frame on my 1980 C10 with 3 wires and it was a PITA, but mine does not have separate lamps so I had to use a logic circuit on mine. Here is a diagram of how I created one with two relays. I connected mine to where the third brake light flashes with the turn signals, but like I said if yours has separate bulbs you should be ok. Just figure out which wire is the brake light and connect the power of the third brake light to that and ground the other wire. I hope this helps.