there are a few things going on, and hopefully I can try to explain some of them. Keep in mind, I am a knucklehead, so it is quite possible I am wrong.
1. Having a higher GVWR but lower payload- the 11000gvwr is for the gas engine, 11400gvwr is for the diesel. The diesel engine weighs much more than the gas engine, hence the lower payload capacity despite a higher gvwr.
2. Your payload- well, Ford is using an XL with NO options as its basis for the 3720 payload. So, how do you get from 3720 to 2860? Well, let's see:
3720
-200 (grill guard/tonneau stuff)
-135 (nerf bars/other stuff)
leaves 3385.
Power everything, bigger wheels, tires, air conditioning, more speakers, carpet/mats, power seats?, more general stuff...I dunno, 200lbs?
leaves 3185.
So where is the extra 325lbs?
You must be fat as sh*t.
Yes, I am just kidding. I'm guessing you weigh around 200, and there's probably more to the XLT crap weight than what I put. 125lbs worth? Maybe not, but I dunno.