You have 2 choices or actually three. 1st choice is to contact your local service dept for your brand and ask them for a wiring schematic. 2nd is to get a few test tools and go at it your self. It can be done with simple tools and a common sense approach. 3rd and easiest way is to buy the mating harness for your truck and use it to wire the new radios pigtail to it. All you have to do then is plug it in. Easy right?
BT ISO DIN