You will have to be careful with any prop you get that is that old. The rubber in the hub is drying and shrinking causing it to slip.
well i finally got my new prop (cost $325.00) and the boat finally goes!! I am not having trouble with the shifter fork, and getting the idle low enough to shift into forward while the engine is idling. Reverse does not hold the outdrive down (the peice is stripped). So a few bugs to fix, but i did go fishing last weekend, and it ran great! Now to polish the boat... Oh yeah i got my prop at Hamilton Port Authority (my prop has a shear pin, not a spline drive)