What makes an item legal for use on 75 and newer vehicles is going thru the approval process to get a CARB EO number or certifying, under the CARB rules, that it is a replacement part that does not change remissions.
Federal law
What slides by is one thing. What costs you $25k if someone turns you in is another.
Nope. CARB = California Air Resource Board
The states that have adopted the California standards are: Connecticut, Delaware, Maine, Maryland, Massachusetts, New Jersey, New Mexico (2011 model year and later), New York, Oregon, Pennsylvania, Rhode Island, Vermont, and Washington, as well as the District of Columbia.
BUT, 68DART360 is in Pennsylvania and they are on that list.
