Here is a good used Neptune antique outboard motor carburetor.  This is Tillotson model MS45.  It will fit many of the mid 1930's small opposed Neptune 4hp and 6hp outboards. These original carburetor are prone to pot metal disease and parts started to break off. This one is not perfect but is in functional condition and it has all the accessories that are often missing or broken.  The choke shutter and the throttle quadrant are especially desirable.  Look at the photos and email with questions.  Thanks for looking.