Slowride, Go to Bass Boat Central & register. Then go to props forum & ask Mark. He is the best there is & the moderator of the props forum. Post the boat &motor setup you have & he'll tell you what you need going from aluminium to stainless. You'll more than likely need to go down 2" in pitch when going from aluminium to stainless. I stayed the same pitch & diameter because I wanted speed & gained 6 mph on a 70 HP Johnson, but hole shot is slow under a heavy load. That's a lot for my little 16Ft. boat. I bought a Stilletto from him for $200.00 versus $330.00 & higher everywhere else I looked. Just be sure to tell him if you want hole shot or speed & he'll tell you exactly what you need .