ID this crank pulley?

Mapco made pulleys for many of the after market AC companies, and not just for Mopars. I doubt that pulley is for a slant six. All of the aftermarket AC pulleys for the slant, that I have seen, are a single shive cast pulley that bolts to the front of the damper. The factory AC pulley bolted to the rear of the damper, and was stamped steel.
My comments apply to cars and most trucks. However I have seen some trucks that have had special equipment added, that have had multi groove cast pulleys.