I did find a Unit Weight sheet in the paperwork that indicates the core weight is 3220, with the addition of a/c (92#), 3 fantastic fans (15#), Gen ready hardware (26#), and duially brackets (20#), the total weight comes to 3373#. So actually the difference is 3936-3373=563#.
I figured it was over by about 500# but was not sure it could be that much.
The workmanship is very good and the people who put them together should be congratulated. On the other hand, management is responsible for these type discrepancies.
Few other things I think Bigfoot could improve in the engineering dept. but they probably have enough going on.
It is a nice camper as a few others have commented.