GM-GMC: 95 GMC SIERRA TAIL LIGHTS, gmc sierra, gmc 1500

Question
HI this is a 95 gmc 1500 5.7L.  My taillights quit working on me awhile ago, i have 4-ways,turn signals, headlights, and brake lights. I have replaced the headlight switch, bulbs (with the correct bulb numbers), Fuses, When I tested the wires at the back of the truck the other day i found no power was going back to lights,(however i still had all the other lights) Where could the problem be at? thanks  

Answer
It sounds as if you have tried just about everything.

The next step would be to trace the tail light wire and look for a bad connection (at a trailer connector, if installed), a bad ground connection, a blown in-line fuse, or a broken wire.

A broken wire can be very hard to find if it is broken inside the insulation.  You may find it easier to run a new wire from the fuse box back to the tail lights.

You did not mention if the front parking lights were working.  They are usually on the same circuit as the tail lights.