That set-up looks aftermarket and Pontiac never offered factory or optional, a rear sway bar that I know of. Is that even a Pontiac rear end? Do you have a pic of the differential cover? Does it have the scalloped sides?
I didn't think so from my research but figured I would ask the experts. It is supposed to be for a 400 4 speed so the dual traction bars seem correct but that is the only picture of it.
Looks stock to me for 1967. All 67’s except the base 6 cyl had one. All manual transmission cars had 2. I am referring to the traction bars alone. The sway is aftermarket.