I question it as well. I've worked on more of those E 250/350 vans than I care to count, and almost all of them have some form of a Dana 60 in them, usually the semi-float version with the 3.55:1 gear ratio. The same rear end can also be found in Dodge B250/350 vans. I do know that they are the correct width for swapping the entire rear, if that is what they meant.
