Looking at 2016 F250 XLT crew cab short bed trucks,gas model shows 2755 payload on door and diesel shows 2122 lbs with a option on it called camper pkg- upgraded front & rear springs and stabilizer ba...
The 250 you looked at has the camper package, which means it is really a 350 with the class 2 10,000 lb GVWR. It will have the same capability as the 11,500 lb GVWR class 3 350.
If you are going to buy new, you may as well get the higher sticker rated 350, instead of ignoring the lower class 2 stickers. Even though the axles and tires/wheels are the same with the 250 camper pkg, the RAWR is lower rated also.