Audio Systems: 86 chevy stereo problems, time fuse, chevy custom

Question
I dont know what to do. I have already cut the stock harness wire to try and connect the harness wire that my DUAL stereo came with. It didnt seem to work . the wires for it is a yellow( constant 12 volt source), red ( connects to igntion circut), and black (ground). The old radio was an AM DelcoGM radio. I diddnt work. It belongs to a 86 chevy Custom deluxe 10 truck. The wires from the old radio  are yellow, grey, and black. I connected yellow to yellow, black to black, and red to grey, nothing happend when i tryed to turn it on. Could u tell me where the proper wires are located?

Answer
That truck wiring is a little different than most. Try this;
Your new stereo red to truck's yellow
Black to Black is OK.
Your yellow to orange at cig. lighter...or full time fuse in fuse box.

Right now, if you turn on your headlights, the radio comes on I bet. The grey is actually for dimmer. The yellow is accessory power (on when key is back , or in run. )