Re: How Much 5th Wheel can I tow?
Well, the 2WD will get you a little better mileage, but if the majority of it's life will have a trailer behind it, the mileage will go out the window. I'd look more towards the amenities and existing miles. Long trips? Winter trips? The capacity between the two are relatively small, but if you're going to be pushing the limit of the 2WD, the 4WD will give you a little more cushion in the stability department, but I don't think it would make much difference in the braking department.
Either truck should be able to handle a 34 footer unladen without a problem.
Chewing on asphalt and drinking dinosaur wine