I measured a brand new 155" 3500 6.0 with no rear interior and the centre wheel hub to fender height was 20-3/4" up front and 23" out back. That means my van has sagged 2" over 15 years including the 1000 # of additional conversion weight.
I had been planning on replacing the springs on all 4 corners but I'm rethinking that now. Replacing the coils and adding lift blocks with overload springs may be good enough. I don't need articulation. Back in 2002 when I drove my 1987 Ford E150 through Mexico, Belize, and Guatemala all I wished for was clearance and a stiff suspension. The clearance was for the speed bumps and the stiff suspension was to take the mountain roads at speed. Many of the big vehicles down there had their wheel stance widened for the curves. Realistically, a stiff suspension is better for speed bumps too. I'd rather get launched into the air over repeatedly belly flopping on those monster bumps...
I had been planning on replacing the springs on all 4 corners but I'm rethinking that now. Replacing the coils and adding lift blocks with overload springs may be good enough. I don't need articulation. Back in 2002 when I drove my 1987 Ford E150 through Mexico, Belize, and Guatemala all I wished for was clearance and a stiff suspension. The clearance was for the speed bumps and the stiff suspension was to take the mountain roads at speed. Many of the big vehicles down there had their wheel stance widened for the curves. Realistically, a stiff suspension is better for speed bumps too. I'd rather get launched into the air over repeatedly belly flopping on those monster bumps...