Just call Quadvan with any questions. Ask for John, he is the engineer and he does the 4x4 conversions.
I was told that the lifts done by Quadvan are 4" or 6".
I have the 6" lift and it is great! Very plush suspension!
I measured 21" from the ground up the underside of the driver door.
Below the driver side door, there is a metal seam.
This is where the outside and inside van walls are welded together.
This is how I got the measurement.
Keep on doing your homework, it is totally worth it!