We had wanted to put a 5000w in the front storage space but the dealer and factory were pretty adamant that the largest we could get was the Onan 3600. As I mentioned before, our Montana is considered a 2002 but we bought it in June of 2001. Now when I see newer Montanas, I am amazed at the amount of room they have for a generator. We like to boondock a lot so our next Montana will also have a propane generator, but definitely a larger one.
It does seem that what was considered "generator prepped" when we bought our Montana and what "generator prepped" means now, are two different things.
Anyways Joe (Castor), good luck. You'll be one happy camper when you do get a generator.