Hi Everyone,
I am not a modeller, but occasionally browse this site to admire your work in comparison to the efforts of my childhood. However, I do have first-hand professional knowledge of this aircraft and can offer the following information:
The A330 MRTT is derived from the A330-200. This is because the -200 has a centre-wing fuel tank giving 33 tonnes of extra fuel capacity, taking the total to 111 tonnes. The previous comments about -200 dimensions are correct. However, different versions of the MRTT are being built for several customers:
1. The RAAF MRTT is GE CF6 powered and has a refuelling boom, 2 underwing AAR pods and a UAARSI (receptacle) for receiving fuel.
2. The Saudi Air Force has ordered the same version.
3. The UAE Air Force has ordered aircraft as above, but powered by RR Trent engines.
4. The RAF will receive the FSTA version; RR powered, but with no boom or receptacle. Some of the RAF aircraft will have a centreline hose.
In addition, the aircraft is competing for the USAF KC-X progamme. The version being offered has underwing pods, boom, fuselage hose, UAARSI and a main deck cargo door on the left hand side.
I guess that the version with least number external modifications would be a UK FSTA without the centreline hose. The aircraft does have several blisters for defensive aids and camera systems though.
Hope that helps.