I have a 1989 Yamaha Pro50 ELF and am preparing to change the impeller and assorted gaskets, etc. In the service manual an unlabeled part below the water pump gasket looks like an O-ring but there's not one included in the repair kit. Since my boat is in a remote location parts-wise, I wondered if I need one before dropping the lower unit. I've read all the posts concerning Yamaha impeller change-outs but most seem to be for newer or bigger engines.
