I converted mine over to a 12 volt system. I used the drivers side alternator and removed the passenger`s. I got a momentary switch for the GP`S relay , and wired the batteries in parallel, replaced the 24 volt starter with a 12 volt.
I payed careful attention to detail in assuring all connections would stay tight and secure for years . I did this for several reasons, 1 being if I were to be away from home and I needed a jump. No one has a 24 volt system,another is that I did not want to spin 2 alternators. Another being that if I were away and the starter or alternator went out I would be stuck,now I have no worries and get better fuel mileage,and have a new starter.
Bite the bullet and just convert it unless you are jumping other 24 volt mv`s with the slave cable,you will be glad you did. I now have put on 35k on mine since, the only glitch I have had is the GP relay went out and I replaced it with a ford starter relay for 25 bucks.