Gas Cap

All kinds of hashed-up misinformation being presented in answer to this rather simple question. LH23H2R's is the only one that's factually accurate so far.

A "vented" fuel cap, by definition, is one that has an unrestricted passage from inside to outside. Most Mopars, including all A-bodies, don't use vented caps. '70-up (California) and '71-up (50-state/Canada) cars use pressure-vacuum caps, which have valve-controlled breathing in both directions, but these are not "vented" caps (wrong term for the cap).

See here for discussion of gas cap interchange ('72-'76 A-body, in your case).

And no, venting the gas cap does not substitute for the removed (why?) vapor canister.