COM)/(ANDO

I have a 1996 Impala, we did a conversion ls swap and sent my wire harness out and recieved a custom wiring harness back that controls all of my impala accessories and connect to my new ls 6.0 Single turbo system engine. now the problem, we were ready to tune, we connected to the OBD and had power but there was no data info coming threw the OBD from the pcm for the laptop. i was able to find the pinouts diagram for the impala J1850-vpw OBD plug but need the pinouts for the ls wiring harness that connects to the GM pcm part E67#12607096 stock computer from a 2007/08trailblazer. Im waiting on the company that did the harness work to call but dont want to reveal there name as of yet. i was told that if we could find at least the pinouts for the data link we could run that wire from the pcm connect to the OBD plug and at least tune the computer. hope i explained it ok im not a tune or wire guy. if anyone can help that would be greatly Apreciated, Thanks.