Also if you have the option when looking at used.
Go for the E450 chassis.
They come in 2 models. E350 and E450. On some of the older models it might say E-Super Duty on the fender instead of E450.
AND when you get into the long ones there is a whole lot overhang behind the rear axles. Metal fatiques and you need to look at the leaf springs.
Bring a flashlight with and get down and really check the leaf springs for cracks or broken leafs. From both sides.
I sure wouldn't dismiss the MH if one is broke/cracked they can easily be replaced by a repair shop. And can be driven safely if one is broke. AND you might be able to get it for a lower price if you point it out to the owner. He need not know that it is an easy fix either. :W