Those are cool. I bought an original one of these a few years ago just because they look neat... I've never owned a car that used one originally, and probably never will... but its one of those oddball parts I thought would be neat to have laying around.
This is another piece I think you will start seeing more and more repros of as the price of originals keeps going up with every one sold. I think these were also used on early 70 Camaro and Nova L78.