A Johnson model FD-19D is a 1965 18 hp outboard.
1965 18 hp
1975 20hp johnson
1968 20hp
1966
I don't have the Mariner year model chart, but close as I can tell this engine would be a 1984 - 1985 year model.
your Johnson is a 1985 year model
A 20 hp Mercury outboard, serial number OB152174, would be a 1987 year model.
An 20 hp Mercury outboard, serial number 3143107, is a 1971 year model.
Johnson outboard model number J175EXARG, would be a 1994 year model.
A 50hp Johnson outboard, model TELCUD, is a 1987 year model.
A Johnson 70 hp outboard, model number J70TLETS, would be a 1993 year model.
A Johnson, model number J10BACDB, is a 1986 year model. 1999