FYI - the pre-2007 E150's were a true half-ton, with an 8.8" rear end rather than a Dana 60, and corresponding 5-lug wheels and smaller brakes. Frame is smaller even. Not the best platform for a 4x4 conversion IMO. And high-roof conversion van is probably at GVWR empty.
The 2007 is when the E150 became a fake half-ton, effectively replacing the E250 which got a corresponding nudge in spring rates to keep in it between the 150 and 350.
2000 E450 dually V10 wagon