I just put a set of #5 drives on my boat. I have an chance to get some props to try but they are for a #6 drive. The #6 prop shaft has more splines and is bigger in diameter than my #5 drive shaft. Is there a reducer that I can buy that will work for me? Thanks in advance

The spline count should be the same; you'll need a 3A, 4A, #5 Merc plastic bushing for each prop.
Due

The bushing part # is 822973. We have them in stock if you can't find them. Also have the c-clips and new nuts.

By the way, your shaft is 1.75" compared to the 1.88" of the #6. They both use 26 splines.