E series duo props came on the DPX drives only, no exhaust thru prop hub. Any Volvo Penta dealer has a nice catalogue with tables that will identify the rpm ranges at different lower ratios for all the F series duo props. Why guess when they have already done all the work and testing?

Ray @ Raylar

c series props fit the swedish drive (270,280,290) they are the stainless model. f series fit the american drive (dp-s) as for rpm the rule of thumb with these props is 300 per number and can be tuned by mis matching a prop shop can take these literally two numbers either direction tell them what you are after instead of buying new ones as these ussually sell new for 1300 a set and 700 on the used market. never heard of f9 interesting sounds deisel