I think the part you are talking about is the prop drive hub. I'm sitting here looking at one of my K&B 61's (mine has a pump) and the drive washer just falls into place once you line it up correctly with the flats on the crankshaft. If you have a boat version with bigger "actual" flywheel it may be slightly different.

You install the drive hub, prop, flat washer, nut in that order.