Ahem,
Guys the A340-500 has something called the RCT, or Rear Centre Tank.
WHich I believe would qualify as an additional centre tank. In fact people who buy this aircraft can even specify the size of the tank if they want it to sretch over 2, 3 or 4 frames in the aft cargo hold.
Hope that helps!!!
Spanner.
P.S. The fuel system on any A340 is a nightmare but ESPECIALLY the 345. Best (for fuel) stick with boeing- 3 tanks 6 pumps! EASY