Re: Identifying a ’80’s or newer Johnson 15HP

[Don]

There were 10/14 commercial models also, some used the 18-25hp gearcase. But, it sounds like yours has the standard style 9.9/15hp gearcase. I don’t know of any beefier components that may or may not have been used in the commercial models. You mention that the engine has the conventional mid section and extension housing, so this seems to confirm that this engine uses the conventional 9.9/15hp gearcase. But, beware, some of these commercial engines had a 22.5" extension, not the usual 20" extension. But, I would think that the extension housing would be missing also, since it had to be removed in order to remove the gearcase. Post a picture of the midsection if that will help.
I’m pretty sure this engine will use the driveshaft without the driveshaft oring, the powerhead most likely has the lower seal housing with the two seals.
And yes, some of the the commercial models came factory equipped with those beefy transom clamp screws.