All of the L engines had the three hole mount in the center of the backplate, however the part number you gave is correct for the L engine. The FZ did not have a crankshaft ring, the L did. You must pull the entire backplate off the engine to see it. The front of the crankshaft counterweight has a full disc with two split rings sitting in a bronze cup which surrounds the rear bearing forward of the crank. If the bronze cup is not there, the engine is not an L. Tough to see what you're looking for, but if you study it a bit, you'll understand.

Good Luck!