Interesting.
I didn't know they were commercially available. We always used "homemade" stuff.
Here's the brackets, on the car:
At one time there were a lot of cars running around here locally with those same style tow bar brackets...
A couple "back in the day" shots:
And - since I still have all the stuff, I put a hitch on my GP for a photo op last May -
That's "how we rolled" back then -