Here's photos of my crank pulley, 3 grooves for a 340 with A/C, same pulley as a 318 with A/C. There are no visible markings or part number anywhere on the pulley.

There were also 2 groove and 1 groove crank pulleys for with power steering and without. 273, 318, and 340 shared the same 1 and 2 groove crank pulleys.

This front groove is cast iron with rubber inlay, and the back 2 are spun from sheet metal.