If you go to autotoys.com they have an adapter to plug into the AUX port on the back of the radio. This allows you to hook up two aux devices and play them through the radio.
You are right.. I am going to leave the factory radio in there, I am installing a car PC in and want to dismantle as much of the factory radio as possible and hide is somewhere in the dash. What I don't want to do is ruin my factory radio so I can return it to stock if I ever decided to part with the truck,like if Hummer decides to put a duramax in them..
Thanks and I will keep looking.