Fuel Dump
just to try to explain this fuel dump business/requirements.
Very few jets in domestic, medium range service need to have fuel dump/jettison capability.
the big thing is if you takeoff , lose an engine and have to return for landing...if your weight is too much to allow a safe go around on remaining engines, then you have a problem...and that problem is dealt with by dumping fuel.
landing overweight isn't so much the problem with the fuel dump requirement, it is the ability to do the go around after the engine out approach.
while there is a rare ability of some DC9's to dump fuel, the changeover in plane size is right around the 767...and some of the 767's DO NOT have fuel dump nor do they require it. but planes bigger than that (just a gudeline) usually have fuel dump capability.