[Greg Reid]

Originally Posted by JimFB400HO

There was a Gustav M. Okeiff in Austin, Texas who died at age 75. (1930-2005)
https://www.mylife.com/gustav-okeiff/e341226135390

That seems like a pretty good guess to me. Definitely Gustav with a middle initial 'M.' and the last name starts with 'O'. How many Gustavs are you going to find in Texas?...much less with the last two initials also a match. Not a bunch I'd bet. Further, next to the 'O' looks to be a 'k' and an 'f'.
He would have been born in 1930 so the age is about right for buying a wagon in '67.
The key could be some hardware store that stamped their name on all the key blanks or something like that.