65 Dart 270 -- 273 - 4 speed

to add: just because you have a fender tag, doesn't mean that it's from that car.

the SO number should be stamped on the radiator support and match the tag. that would indicate the tag belongs to the car.

the early cars don't have motor/trans that are numerically tied to the VIN, so the best you can do is decode the numbers on the block and trans to see if they're correct within range of the build date.

so between those: fender tag matches what the car purports to be, parts in the car match the tag, and parts are of the correct time frame for the build; one could reasonably say it's legit.

or somebody went to a helluva lotta trouble to get there.

but if i was spending big dumb money on a "one of car" i'd want a build sheet or some other kind of documentation to back up the provenance.