seeking recomendations for a towing vehicle that will seat 7

Thanks,
a couple of quick questions.

Land28BH -
if i get a used one, do the all have the standard CAT 4 towing hitch (is that the word?) ? is that something that can be installed out of the factory on a used van,
or do i need to be looking just at ones that already have the hitch?

also a newbie question, the 3500 6L you mentioned, is that a diesel engine?