Our boat is hull no. 21 and a local boat hull no. 250, Bernie Yau's, does not have the aluminum backing plate as shown in attached image. If there are no others I would assume that a PO has perhaps installed the M12 transmission which has the output shaft 10mm higher than original HBW50. Unfortunately history is lacking on our boat. And yes, I know the new regs. say the primary filter should be outside the engine bay. This is a work in progress.
thanks,
George
thanks,
George