Gas Cap

Belvedere66 said
70/71 models with ECS and 72+ models will have a "vented" cap with 1/4" tangs.

No, '70+ cars with ECS do not have vented caps. They have pressure-vacuum caps. It's not the same; see here. Also, the '70-'71-with-ECS gas cap is not the same as the '72-'76 cap.