after doing some more research I have found the solution... I think
evidently later model GM vehicles (do not know the year change) have a updated communication language. the newer vehicles have what is called "CAN bus" and I guess requires 2 wires - hence circuits 2500 & 2501. the newer replacement connectors have a 5 wire pigtail. below is the connector I ordered. the CAN bus wires are included as well as the "regular" or older communication wire(s).
link:
https://www.ebay.com/itm/142515602351
pin info:
2 20ga PPL CLASS 2 SERIAL DATA
4 18ga BLK GROUND
5 18ga BLK GROUND
6 20ga TAN/BLK CAN (+)
14 20ga TAN CAN (-)
16 16ga ORN BATTERY (12V)