The mpems are different because of netural safety swich and netural rev limiter. You can use a gtx mpem with some fairly simple wiring and loose the netural only start and rev limiter in netural.
Where would I find out how to do this simple wiring? The vendor selling units could not give me any help- they said "it is for GTX only". Will the color codes match up for at least some of the wires?
Seadoo source or something like that has the MPEM for sale now he doesn't have any left but if you contact him he will give you the information about the conversion kit and how you go about doing it
Thanks for this super helpful info. I'm busy with harvest and put the boat stuff on back burner, but will definitely be making use of this info when I get back to pulling wrenches.