Merc 400 outboard???? Help needed

I bought my son a trailer for his 12 ft alumicraft this afternoon, the deal was buy the trailer take the boat and motor with it. Cost 50 bucks. The motor is a Merc 400 outboard, I know nothing about the motor except the people said they bought the boat a few years ago and have never tried to start it, the boat is a 13 ft fiber glass boat unkown manufacturer, does anyone have a suggestion on getting info for the motor, I do not think we would keep it and may sell it. Help, Thanks