Three's A Crowd
The photo in post #4 shows two supports. I am beginning to believe the factory only installed the forward one.
Edit: Above statement wrong--there are two braces, not one. Per diagram in FSM page 9-1: "Engine External Parts (V8 Cylinder) - 273 Cu. In. Displacement
and
per parts listing in FSM page 9-46, section 9-48-155:
Brace, Exhaust Manifold, Left to Cylinder Block, V2, L2 ... 2465 162
Brace, Exhaust Manifold, Left to Cylinder Head, V2, L2 ... 2465 161