only the 66 and earlier ones. IIRC they are an inch wider on the perches, and an inch wider on the track-width, which seems to be close enough.
But my memory may not be all that accurate.
Isn't there also an 8 1/4 and 8 3/4" that would fit the 1968 dart without any modifications. Didn't some a bodies come with the 8 3/4"? Is the 7 1/4" sure grip more durable that the standard?