I have a restored '57 18HP Johnson where the seller who restored it says that he used a newer 25HP powerhead but at one point wasn't sure if it was perhaps a 20HP powerhead (the original 18HP powerhead had a bent crank so he replaced the complete unit). Thinks is a '69-'70 vintage unit.<br /> Can I know the exact HP rating by an engine # stamped on the block? I have several old Johnson repair manuals but they don't specify HP ratings by any #s stamped on the powerhead unit itself.
