I have a merc.150 hp engine which I will most likely part out as there is no title,it has been in storage for about 15 years ,the only ser. number I can find is 39 sm1-89, I do not see a welch plug with a ser #it turns over by hand so I wiil check the compression next...can any one help id this engine,thanks oops I think I posted in the wrong forum,sorry