Do not compare 2014 and earlier Fords to 2015 and newer. Numbers have changed alot between them. Especially the F450's between 14 to 15, not even the same pickup, not by a long shot. 2015 F450 actually sits on a 450 chassis for 2015.
2011 to 2014 F450 is basically just a F350, more like a F355. Bigger breaks, slightly different front axle and I think one more leaf in the rear. Everything else is the same between the 450 and the 350 for those years.
2014 Cedar Creek 38FL
2012 F350 DRW,