I was told many years ago that the problems with the MPC kit stemmed from the source images that were provided were from squeezed anamorphic frames, which compressed the apparent length of the shuttle, therefore making the body and vertical stabilizer too short from front to back, and the angle of the cockpit too steep. Somehow, Kenner got the proportions right with their rendition of the shuttle, which looks closest in relation to the studio model.
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