For before 1960-1990 Mercury/Mariner 2-cyl, 6-40 Hp | 3-cyl, 50-60 Hp | 4-cyl, 40-50 outboards.
ID: 0.0937″ | OD: 0.2812″ | W: 0.0937″

also crosses with:
Sierra: 18-7197-9
GLM: 81030
Mallory: 9-76561