Re: Mariner 15 Hp what year?
I can only hazard a guess that you have three other numbers in front of the 552327 and they should be 684, therefore the s/n would be 684-552327 and would come up as:
15C EL 684-551876 - 1983 (1983 mean all other s/ns after 684-551876 were made in '83)
Can you verify if the 684 numbers are there?
Gerry