So when did the word “Bump side” become a thing ?

Until recently, I had never heard a 67-72 Ford truck described as a bump side. Is this a new thing , like “square bodies”? Just curious…

 

Not a blue oval guy, but I've only heard it in the past couple decades. It may have started earlier.
Just another bit of easy to say slang. Bump side VS dent side. Just like Deuce, highboy, and slammed, intended to convey a particular thing in short hand.

 

Bumpside, dentside, bullnose, bricknose, OBS. All different nicknames for different generations of Ford pickups.