Hot wire?

I hope someone can help. I just got a "Peripheral" Brand Ipod integration for my 2004 tahoe with Bose. I got everything set up with the exception of needing a constant power and a ground. Looking at the other wire harness(larger of the two) on the back of the radio, can anyone tell me which color is the power and which is the ground? I have heard orange is the power but there is a thicker and thinner orange. I just don't want to screw with it without knowing for sure. I don't have a meter and I have been doing searches for wire diagrams with no luck. Worse case scenario, I'll pay best buy the $60 to install but seeing as it is only two wires holding me up, I would rather do it myself and save the $60 for some Sam Adams Octoberfest!! If any of you stereo experts could help, I would appreciate it.

Orange is constant +12vdc and black is ground. Use the larger of the two orange wires on the main harness.

Thanks. I figured that the cigarette lighters always have power that I would tap into one of those and just as you said, orange was + and black was -. I appreciate the feedback. Now the ipod sounds great thru the Bose. Much better than that FM transmitter.