50/1 usually in those years
before you start it
check or better yet replace the impeller …. change gearcase oil and check for water intrusion if you have water you will need to reseal the GC … use new nylon washers when closing it up
pump it up with fresh gas and try it out … check water pump operation you may need a carb job (not complicated) if rough
post mdl #…. I found no 1968 15hp Johnson listed
Joining AOMCI has priviledges 🙂
