'98 Johno 40HP what pulse/rev alternator?

[Blue_Escape]

Hi,<br />I want to fit a tacho onto my electric start '98 Johno 40HP 2-stroke outboard. Looking on ebay but not sure which is correct model / part number? Some state "5-6 Pul/Rev Alternator"...would this be what I need???<br /><br />Cheers<br />John