BLKNIGHT:
There is a Body Control Module located to the right (pass side) of the gas pedal. The BCM has 3 plugs (1) Brown, (1) Light Blue, (1) Purple.
The plugs face the drivers side of the vehicle.
In the Brown plug pin #B4 if there is an orange wire, it should have the keyless option.
Pin B4 the wire is orange. Pin B3 is a Red/wt wire, and pin B5 has no wire.
another option would be to call the parts dept of your local GM dealer, and give them the VIN #, they can plug that into the computer and tell you if it had keyless.