Well for the E450 the GVWR would indeed be 14,500lbs which would make the GCWR 22,000 lbs.
See here:
2017 E-Series Cutaway | View All Specifications | Ford.com
Keep in mind, though, you still probably only have the 8,000 lb hitch thus your trailer could be no more than that even if the GCWR may allow something greater.
I'd also take my unit to a scale (I've weighed ours) just to see where you are at with respect to weights.
Thor Forums
