I'd call GW customer service and have your hull ID available for them. They'll help you out so you get the right sender unit. Also, there was a Seafarer safety recall a couple of years ago pertaining to the senders - I THINK it was bad gaskets that had to be replaced if I recall correctly - you should check if it applies to your boat.
I have a 1996 226 Seafarer and replaced the fuel sending unit last year with a WEMA SSS/SSL 14 inches long. I called Grady White and they gave me the length.
I had to replace one of those last year, did not know about Wema at the time I bought it. I ended up buying the exact OEM from some outfit in the Pacific Northwest (Seattle??). Bottom line - because I rushed getting the unit instead of looking around and asking these guys, I ended up paying about $100 for the OEM when the Wema unit would have worked at 1/3 the cost.
