i recently acquired a 4hp evinrude model#4536A long shaft,i notice at the bottom of the gear casing that the extension adapter that makes it a long shaft is removable.i went on there parts list and notice that the extension has a bunch of parts also but my question is........whats needed to make it a short shaft?do i need extra parts to do this or simply just remove the extension that makes it a short shaft.another words is there a separate drive rod or does the extension just adds to that drive rod shaft to make it longer.......its a little hard to explain i guess...did anyone else do this?thankz for the help