I'm replacing a 12/24 volt Motorguide (48 lb thrust) with a new MG W75 wireless.  I want to remove the old plug and use it on the new motor so I can plug into the same outlet in the bow without having to change anything.  The old plug is a four prong, three wire type and the new motor has only 2 wires.  Is this is simple as it appears or am I neglecting something.

Simple - determine postive/negative in the outlet and match those poles on the plug. Present outlet configuration is a positive 12 volt, and positive 24 volt, and a ground. Remember to use the 24 volt positive.

If you have a $10 multi tester, you can determine which is which very easily.  If you get the wrong one then you will be trying to run a 24v unit with 12v.