Frankentanker uses bits from several different airframes?
I don't understand this whole "Frankentanker" fetish.
If the mission calls for a short fuselage, then yes, you start with a -200. MRTT does the same thing. But if the mission also calls for higher gross weights than a -200, then obviously you use the sronger landing gear and wings of the higher gross weight -300 version. And if the mission calls to operate into and out of shorter fields at higher weights, you use the high lift system from the -400 version. And if the mission calls for a cargo door and floor, you use the cargo door and floor from the freighter version. What is Frankensteinish about that? It's just plain good engineering to use an existing design that is proven and works rather than start over with something new. It's the same reason the KC-46 uses a modified KC-10 refueling boom. It also uses existing off-the-shelf wing aerial refueling pods and cockpit displays. They're proven and they work. Nothing Frankensteinish about that.
The various iterations of the 737 BBJ do exactly the same thing, mixing and matching fuselage length and heavy or light weight landing gear and wings to fit the customer's needs. That's also what was done to create the Wedgetail and the Poseidon, both based on the 737 airframe. It's good business
and engineering practice, not freakish.
Earlier in this thread it was noted that the MRTT can be equipped with the freighter's cargo door. Is that Frankensteinish? An argument can be made that it might be because an A330 with the freighter's cargo door but not the freighter's cargo floor nor the freighter's nose gear is kind of a freak. What's the point? And is flying around in a two engine airplane with a wing designed and built for four engines freakish? I don't think so, but apparently there are those who would say so. And is having a large airframe tanker with no boom to refuel UARSI equipped aircraft freakish? I don't think so, but it might be penny wise and pound foolish operationally. Even ancient KC-135s can go "both ways".