It sounds like you have an ambulance with dual alternators. No need for dual alternators, so go with the 200 amp alternator. 200 amps is a LOT of current!
I sold my 2004 F-350 about 7 years ago. I did not need that big of a truck. I bought a Toyota p/u and kept it for two years and got rid of it. I just don't need trucks any more and if I do I can rent one...
Smog laws differ in each state. California has the toughest laws in the Nation. We pay a lot to keep our trucks registered here. A truck that you buy in Idaho, for example, can not be registered in California. BE CAREFUL!