Keep in mind too high of a GVW may limit the streets you should drive on. Weight limits can be based on actual total, actual axle, liciance plate rating, or listed GVW. Every area here is different. A number of residential streets here have a 12,000 max GVW limit.
It's my understanding that if your listed GVW is 14,000 and you drive on a 12,000 max GVW road even if you weigh less than 12,000 you in trouble.
Those Dodge Cummings diesels are great but they never came in any van set up.
Diesels also have a better resale value.
In Illinois you don't need to do emmision testing/repairs if you have a diesel. I think med duty trucks are exempt too.
Try looking at step vans too.
http://www.freightlinerchassis.com/wv_default.asp?page=wv_mt45fab&nav=mt45 Tom