I'm looking at an ad for a Mariner 40hp and all the guy can tell me about it is that it was running when removed. I ask for the serial # and if he knew if it was a long or short shaft. He sent me the serial # 0C187896 and HP30JET. I haven't been able to find out what he has. I'm looking for a short shaft for my 16ft river boat and don't know how to tell if I go look which it is. Any and all help would be appreciated. The picture from his ad says its a 40hp.