The F450 comes in a 14k lb pickup and 16.5k lb chassis cab configuration. If you choose the the pickup, you get the lower GVWR but higher tuned engine and upper end trim levels. Ford made the F450 pickup for those that need a chassis cab but didn't want one due to limitations or lack of pickup bed.
When I was shopping, I found that an upfitted F450 or F550 chassis cab would weigh over 10K lbs empty. Once I added a 6000 lb camper and 1000 lb of tongue weight, even the chassis cab F450 GVWR was not enough - This is why I ended up shopping the 5500/F550 class. It also gave me the freedom to add 600 lbs of batteries to the truck without even worrying about GVWR limits...
