LIM-IAH on the 767-300 used to routinely bump up against max ZFW. 40,000lbs ++ of fish, flowers, and asparagus in the belly will do that to you. The flight is only 6 hrs, so light fuel load. The TOG might be 40K below MTOG, but you're maxed on payload. Done. Bad deal for SAs.... they see open seats, but are left at the gate.