I bought a Laser II stainless prop for my XR-2 V-6 150HP. Took off the old prop, slid the new one on, and...the aft portion of the hub has no detents to catch the locking tabs of the washer. Dug around in the boat and found what appears to be an adapter--catches the aft portion of the spined shaft and has the detents. But, is this meant to be used with or without the front thrust spacer? Without the thrust spacer the prop goes pretty far forward but the aft adapter gets a good bite on the splines. With the thrust spacer, the prop "sits" about right relative to the lower unit, but the adapter barely gets any spline at all. Hmmm...