They were popular back then more for style and they had to be that tall if you were in the mountains. But they do extend and unexdend much like the front fender mounted ones and are the same except the mounting base is at a 45 degree angle. They can go from 22 1/2 to 57 1/4. Have a set from an old newport from the junkyard and are the exact same as the one on my dads 68 Charger.
I can take a picture of the base tomorrow if you would like.
