All 747s have the same base cost.

I think the 74D also has a higher MTOW - but I'm not too sure about that one

One would think

Uh ok, SO it's good for short heavy routes.

BTW, do u know if it uses the same maintenance base as the 400?

Less fuel, more windows on the upper deck, and designed to handle more cycles (more frequent flights) per day, like redesigned landing gear, no winglets (added weight and stress), etc.

EDIT: Also, technically, AE doesn't really take into account MTOW and all the weights. Technically, you can't get a 747 with 500+ pax to the full, max range (at least with baggage).

According to wikipedia. they reinforced the structure for longer life of the aircraft due to the amount of cycles the aircraft performs on domestic flights.

 

I think it includes wing reinforcements ,  extra frames at landing gears etc. resulting in a higher weight of the aircraft thats why the range is shorter. max pax according to wikipedia 568

I imagine the longer range 747 would have fuel stored in the belly I could be wrong. That's why I was thinking it anyway.

Probably they indeed kind of deactivated the center tank but that shouldn't make a difference of 5000 miles. I know on the Airbus 330 they made the center tank not usable on the -300 series resulting in a longer aircraft and more pax. -200 has a center tank but is shorter and less pax for longer range.

 

But apparently pax is the same on the 747-400D as the -400.

Don't understand it neither. 

Uh they took the fuel tanks out? As far a I know the fuel tank is an integral part of the wing structure.

I imagine the longer range 747 would have fuel stored in the belly I could be wrong. That's why I was thinking it anyway.

They took a load of fuel tanks out to lighten the weight. So Domestic operations can have a lighter load, thus a lower fuel flow.

 

Uh they took the fuel tanks out? As far a I know the fuel tank is an integral part of the wing structure... 

The caveat here is that (in the game) 747-400D has similar fuel flow as normal 747-400s.