I Have a mercury 1983 70 hp outboard Im trying to find out if its a 20in. shaft or 25in.shaft.I have a serial#6230721 but I dont know where the model # is can anywone help me with this.<br />Thx.
Measure it from the inside top of the clamp to the AV plate, byeager10. The distance may not be exact, but it will be close enough to tell if it is a long or extra long shaft engine.<br /><br />Good luck.
the shaft length is measured from the bracket where it hangs off the transom to the anti-ventilation plate (the flat part of the outboard's shaft just above the prop). Your motor should sit so that the anti-vent. plate comes just even with the bottom of the boat.<br /><br /> shaft length diagram
