I believe they chose the E350 instead of the E450 is because the E450 chassis is 4.5" wider and The Axis is only 96" wide at the back. I checked one out at a show and did not like the flimsy bathroom double door and large windshield. I had an A and that would let in a lot of sun and more area to get stoned. After switching to a C I like the fact that I have a nice sun visor (overhang) easy windshield to replace, airbags and our own doors. I didn't like the fact the front dash was so far extended and hard to judge and see compared to the C. I did like the twin rear beds and couch though.