As best as I can recall, the propeller used on the 1967 model, 50 hp Mercury, was of a splined design. If there are splines on the engine propshaft, then no shear pin is used.
A human has approximately 20 teeth which can be considered as splines.
My Dana 35 is in a 98 ZJ with a 5.9. It has 30 splines.
answer is 30 splines
To replace the propeller seal on a 15 HP Mercury outboard, first ensure the engine is off and securely supported. Remove the propeller by loosening the prop nut and sliding the prop off the shaft. Next, take out the old seal from the propeller shaft housing and clean the area. Install the new seal, making sure it fits snugly, then reassemble the propeller and nut, ensuring everything is tightened properly before testing the motor.
Many small aircraft have 1 propeller.
10
Jew Jew Jew
23 Splines. See the Novak NV3550 knowledge base. http://www.novak-adapt.com/knowledge/nv3550.htm
56mm diameter with 8 splines, what sizes are the spline widths
Donald E Amos has written: 'Quadrature subroutines for splines and B-splines' -- subject(s): Splines
27 same as a th350