Seamiad, Delco and Delco-Remy (two different companies) both have toll-free numbers and will gladly help you to identify your alternator, and then wire it up correctly. They have most of the technical materials available online as well--but they're really, really, helpful folks.
If that is a standard alternator, it is only meant to charge one battery/bank. Making it
work properly for two involves some choices and compromises, you can see those detailed on Blue Seas' and other
marine electric equipment web sites. Battery swtiches,
power combiners...a number of options to suit your
budget.