Welcome to the Truck Conversion forum. That's a great decision to buy a HDT (heavy duty truck) to pull the 5ver! There is actually a pretty good size group of people doing that. The best forum I've found for this type of discussion is over at the Escapee's site: http://www.rvnetwork.com/index.php?showforum=32
I'd take a look around there and do some searches and I'll bet the info you're looking for will be there. You should definately consider coming to the National HDT Rally! HDT Rally
. The group is very very nice and you'll have a great time. You certainly don't need the hdt to attend either. I've been to the last two and there are always people attending that want to research before buying. And, often there are people that have rigs for sale (either upgrading or getting off the road).
Hope to see you at the Rally!
'03 Freightliner FL112, 295" wheel base, with '03 United Specialties 26' living quarters, single screw, Cat C12 430 h/p 1650 torque, Eaton 10speed , 3.42 rear axle ratio