Sierra Drain Plug

 3/8" -16 thread
Mercury: 10-20259, 10-28634, 10-28634A1,
10-79953A2, 10-79953Q2, 10-79953,
10-79953Q04, 816610A1, 816610A2, F40109,
10-F50109
Includes gasket 18-2945