What does the original gas cap look like?

[munsonbw]

I am trying to get to the bottom of why the gas tank on my '68 is collapsed. I have a feeling that the gas cap that is on it now is not supposed to be. It is not vented, just a flat cap with two tabs sticking up to turn it. It does have an aftermarket electric fuel pump, but it puts out 5 psi.

Any pics would be great.

Ben

 

[edge4]

For 66-71 the caps were vented, 72-76 had overflow tanks and charcoal canisters.
Pic courtesy of JBG:

 

[munsonbw]

Thanks Edge, that's what I thought.

Ben

 

[edge4]

Ben,
By the way, I forgot to mention that you can find both types at most auto parts stores. I found them at Pep-Boys for 5.00 each. Stant brand 11702-(non vented) and Stant 11048-(vented). They are not interchangeable. The vented has a shallow ring depth where the non vented is deeper.
Edge