Who knows their chrome air cleaner details? Did the CAP nipple exist all 3 years, 1965-'67? Are there any "tells" on original VS. reproduction decals? Did Dodge use the chrome air cleaner on anything or is Plymouth the only application?

Second question, no.

Third question, if you're talking about the Commando 273 dealy, it wasn't a decal, it was a piece of aluminum kinda like a pie plate but with an open middle, that was glued to the air cleaner top. If it's a decal, it's a reproduction.

Last question, they came in Plymouth and Dodge versions; Plymouth version said "Commando 273" and Dodge version said "Charger 273." Same air cleaner painted black with no pie plate was used on various early 60's big block 4-barrel engines, and with a different base on various slant sixes.