Yes they came on a dart. Just that they look completely different 1970 to 1971. There are two styles.
That picture you posted is a rim blow style that was optional on some 71 A bodies, 71 B bodies, and 70-71 E-bodies. Horn button inserts change between some of those years and models.
The picture I posted is from Alaskan TA’s Hamtramck-Historical link. The 70 A-body rim blow is on lower right hand side. That rim blow was optional on 70 A-bodies and 70 B-Bodies
