I just noticed something, and it's a bit odd. But, the numbers in an old AM radio, exactly correspond to the positions in an old 3 speed transmission. If someone figured out how to pull it off nicely, PRND21 could replace 5,8,10,12,14,16

yes, I see that this automatic has a reverse manual valve body, and the shifter gear indicator is accordingly adapted, don't get distracted with that on my little conceptual notion here. 

IF a person were to be a bit daffy, and want to make a strange custom feature on some car that was going to be on the show circuit, couldn't you see a push button transmission, unlike any other, as no one has ever done this thing I'm postulating, as using the AM radio dial and buttons to select the transmission gear? 

Just reprint a dial for the radio, and have is display PRND21 instead of the radio frequencies. 

Then push the button for the gear you want. 

Since no one uses 1 or 2 anyway, as automatic type people just select drive, reverse, or park, there would need to be some sorting out of the 5 buttons of am AM radio. Or just find one mane with only 4 buttons.