Sorry if overdone but I know that with old Mercs, one can know year and more by the serial #. From what I've seen so far, it's not so easy with Johnson/Evinrude in comparison with old stuff (late 50s).<br /> I know that my outboard has a replacement powerhead but not sure as to exactly what I've got. According to my '57 18HP owners manual that I recently purchased, the serial #s on the blocks freeze plug and tag under model # should match. Mine don't. The tags serial # is 224213 and the blocks # is 1722161 (so should be newer).<br /> Anyone have specs that list anything by serial #s?