If it is an E350, maybe. Those come in 3 wheelbases and the short one is 138" just like the vans.
E450s only some in 158" and 176" (and often is stretched longer up to 223").
I have seen one E350 wagon body dropped onto an E450 frame. He cut the front doors mid-way and spliced in to the cutaway cab. It looks factory when he was done, kind of like an extended cab pickup. They even opened. He obviously was good at body work though.
I've though about doing the same (those chassis are cheap!), but my approach would simpler. I would cut the donor body at the B-piller, and fill the space with a cab extension.
http://www.cabbacks.com/about.html