Czarbecue
Babbling Farker
Not sure of the exact thickness of the firebox but it is thinner than the cook chamber. Not sure of the exactly sure of the upgraded fire box but I believe it is a thicker steel and the vents are steel as well instead of aluminum. I will measure the grates tomorrow and get you a square inches of cooking surface.
I believe the FB is 1/4" while the cook chamber is 3/8".