l/u 1971 merc 650 4cyl

[hawgslayer75]

Sorry guys I know u have been asked this a 100 times probably, but I need to find a l/u for my motor I don't know what years inter change with it my l/u # is (1623 4934) 3 . I don't know if that helps or not . I measured the drive shaft it was between 20"-20 3/4" my drive shaft does not have a nipple on top of it, all lower units I'm finding do have a nipple will it work with my motor or will my drive shaft work in those l/u. Thanks for your time & help.