Double tab gas caps?

A-body gas caps don't interchange across the lines formed by these groups:

• '60-'66: Unvented cap. Single set of tabs on small-diameter/shallow hub

• '67-'70 (except '70 California): Unvented cap. Single set of tabs on slightly larger/deeper hub

• '70 California + early '71 50-state/Canada: Pressure-vacuum type cap, single set of tabs on larger hub

• Late '71-'76: Pressure-vacuum type cap, two sets of tabs on larger hub.

Find pressure-vacuum cap info in this article.