1970 Challengers w/o N95 had "NOT VENTED" gas caps
1970 Challengers with N95 had "PRESSURE/VACUUM" gas caps

N95 was E.C.S. - evaporative control system - basically mandatory in CA only "California Emissions".

In 1971 all Challengers had a similar emissions package but were the parts the identical?

My '70-'71 parts catalog makes this clear as mud ...............

FUEL TANK, CAP, Gas Filler Tube, WITHOUT VAPOR SEPARATOR
1970 - Challenger chrome flip top - #3404 657
1971 - Challenger chrome flip top - #3466 435 Why 2 different part numbers?

Is "WITHOUT VAPOR SEPARATOR" the same as w/o ECS?
& there is no listing for a non-flip top gas cap "WITHOUT VAPOR SEPARATOR"

FUEL TANK, CAP, Gas Filler Tube, WITH VAPOR SEPARATOR
Challenger chrome - #3404 528

I know the non-flip top cars came with a body colored cap and the replacement was chrome.
Is this that cap? Again, it is only listed under "WITH VAPOR SEPARATOR"?
Shouldn't there be both a not-vented and a vented (pressure/vacuum) part? At least to cover '70 & '71?

FUEL TANK, RING, F/Tank Filler Cap Ornament
Challenger - #3404 666

FUEL TANK, CAP, Filler Tube (Locking Type)
Challenger - #3404 668 written in pen - is this the correct number?
Challenger EXPORT - #3404 683 "NOT VENTED" & NOS on Ebay

Clearly definitive information!

Anybody have pictures of a "PRESSURE/VACUUM" cap, what are the differences?