Hi: I am putting this engine back together after rebuilding a frozen pinion gear and bearings. Bought LOTS of pieces new so to be sure all will turn free etc. The lower unit was removed from the ‘whole’ when I acquired it and apparently one piece was missing in the acquisition. It is called out as PN ’69’ 305571 ‘Adapter Model RDSL’ obviously only for use connecting the 5″ extension piece to a normal (short) shafted engine. This piece is machined from one piece even though in the attached pics it looks like the ‘sleeve’ part slips through the larger piece. One of the ‘sleeves’ on one side is longer than the other. Which way up? Also, while the piece fits into a socket in the bottom of the extension piece (#68) it seems to just ‘rest on the shoulder of the water pump,(they are same OD) sort of just continuing the tube which contains the drive shaft. This doesn’t seem right to me that it just sits there. I originally thought that an o-ring (#7) that fits over the top of the water pump assembly somehow connects the bottom but that o-ring seems to do nothing but go over the top of the water pump housing that contains the pressed in seal. I can’t figure out any reason for this 0-ring (#7) to even be there at all. Hope someone out there has a bit of experience with the long shaft version. Thanks Tom Alexander