The Luftwaffe already operated the A310 MRT in 'combi' fit before the tanker conversion. The additional fuel for the tanker conversion was carried in 4 x removeable auxiliary tanks in the lower holds, although it would have been feasible to have included a 5th tank. The upper deck freight floor and rear passenger seats were retained, so that the aircraft had a wide variety of possible operating fits.
Luftwaffe AAR is now provided by the A330MRTT, operated by the multinational tanker force at Eindhoven and Köln/Bonn.
Even in the non-freighter variant, the A330MRTT has prodigous lower hold space for a wide variety of freight options and is fitted with large lower hold doors, so that there is no real need for the upper deck cargo and cargo door option.