When I tried to e-mail you to enclose a picture of some new old stock lower unit parts (we do have a propeller shaft, a vane style water pump housing, etc.), the e-mail failed. Is your address correct?

22 tooth gear for single is 43-24437
19 tooth gear for twins is 43-24438
Mercury revised part numbers
Old number is part 55 prop shaft gear from
prewar owners manual price list
I believe also a postwar part numbering system
in between as I have a Mercury photo list
that refers to KF5 prop shaft gear as M-50-203
Apparently Mercury renumbered everything to
mesh with a parts system adopted in early
1950's...dealers probably pitched all the
old paperwork about that time accounting
for sparse supply.
Louis