where to find 8.75 sure grip units used

I don't know if there is such a thing as a Mopar that commonly has a sure-grip. I say that because in most instances it was an option, even in a lot of their performance vehicles. A perfect example is back in high school a buddy of mine had a 67 Dodge R/T with the 440 magnum and nearly every option available including an 8-3/4 but it was a peg leg with 2.94 gears. Not sure why someone would order a car like that but that's the way it went back then. The really odd thing is you can find them in vehicles that you think may not have one. Such as Chrysler New Yorkers, 1/2 ton pickups and I even saw a 71 Duster with a 318 with no other options except a 3:23 sure-grip. You just have to check everything you see cause if you don't you may miss one.

BTW: You know you can buy new ones, right?