Re: 1956 Johnson 10 HP ??
That B is there to make lots of people like you ask. Seriously, it is there to indicate any mid-year engineering changes. And there were several in 1956. Only matters if you happen to be ordering one of the affected parts. The parts book will tell.
More than 10hp?? Got a dynamometer? Actually, a "10hp" Mercury of the era will probably run circles around it, so don't get into any races. The Mercs back then were notoriously under rated.
