EngineerJay

I am working on installing a new radio. I am trying to figure where to get the constant power for radio memory. I have a 71 and on the original radio connector there is a black for gnd, the yellow appears to be a on with ign and a gray that looks to just be on the same line as lights.

Thank you!
Jay

Mooser

Handy to the radio there should be constant power to the clock and also to the lighter (double check, I'm pretty sure it's constant). I'd go for the lighter. (not true, I actually ran new wires over to the fuse box for the radio)
Mooser

leadfoot4

Go to your fuse box. There are one or two terminals that are "constantly hot", and make sure you have an inline fuse between the fuse box and the radio....

Lou64

I'm assuming you are installing an aftermarket radio? There should be two "powered" wires going to it. The yellow is the power from the ignition on position. There should also be a red wire that will power your head unit in the "ACC" position. If there isn't one there, you will have to make one. Find the ACC wire coming out of the back of your ignition switch and splice it and run to your red wire from the back of your head unit. Those are the only power wires you will need.

Always attach the ground wire first. Birdcage makes a great ground.