Bill - Picture posting has been fixed. You should be able to add them by editing your post.
On the question of Chevy having a spacer plate under the "Octane Selector" assembly, everything I searched this morning (prompted by your email
), says Chevy didn't have such a critter. I looked through both a Chevy Parts Book ('54) and Shop Manuals ('42-'47, '48-51 and '54) and not seeing anything like your GMC spacer (screenshots attached).
