Ls swapped, but no OBD2 connector?

[Jmiller022]

I just bought a 68 stepper with a 5.3/4l60 in it and it runs and drives great but there is no OBD2 port for me to hook into for tuning changes to be made from the PCM.

I asked the guy and he said he never got around to wiring one in since he was staying completely stock.

Is it a separate harness? I assumed it was part of the main harness.

If it is separate, how would one got about getting said harness and then how would it wire in?