I have a 1985 Johnson 115 hp J115TLCOS. The lower unit went out. I was fixing to order new gears for it and discovered the lower unit isn't the original. I have tried to cross reference the gears that came out of it, but I'm having no luck. Is there any way to identify what year the lower unit is so I can be sure I order the correct gears? Any help will be greatly appreciated. Thanks.