Speaking of the intertank, people don't realize the importance of that structure. Let me explain a little.
You have two solid rocket boosters which are each pushing the intertank with millions of pounds of thrust. There is a huge 32' +/- long, 6' tall in cross section (IIRC) structural box beam going through it from side to side with a monoball on each side where the boosters push the tank, which in turn, pushes the orbiter. (The term "shuttle" refers to the boosters, tank, and orbiter.)
The beam transfers the thrust load from the boosters to the intertank. The intertank pushes the LOX tank (the pointy part of the tank), and "pulls" the LH2 tank behind it. The LH2 tank pushes the entire orbiter at the aft attach points.
That intertank is the very heart of the shuttle itself, structurally speaking. It must certainly flex somewhat as loads change due to wind shear and such.