2000+ cheverolet programming stock radio

Hi. I am replacing the stock cd radio in a 2000 chevy venture, with a stock cd cassette version of the same radio. These radios one require "marriage" to the cars BCM using a tech 2 scan tool. The dealer tried and after an hour decided that the new piece was meant for a Hummer and would not work in a Venture. I have a feeling he may just not have known what he was doing. Any detailed info on this matter would be greatly appreciated.

Are you referring to the class 2 wiring design?  If so, there's more info on that stuff here.

Thanks but that link only explains about replacing with an aftermarket unit. I need help programming a new stock radio to the car's bcm. Any help is appreciated.