what year is it?

I have an older yahmaha outboard motor and I'm hoping that someone can tell me what I have. It was given to me by a friend whos father had obtained it in the military. I've tried numerus yamaha web sites world wide to no avail. It is a 25hp enduro model 25cm. I hope some one can help me so that I can try and obtain some parts to get it running again. Thanks for any help offered.