Hi Kathy,
I am also researching this line. My descent is through their daughter Susan, b. 1950 and died in 1944 at the age of 94.
William's wife was Canzada Shelton. Her name has been mangled many different ways, but it is a repeated name in the Sheltons, who also settled in Miller County.
I have no idea what happened to William after the 1950 Census.
Please let me know if you have learned any more in the meantime.
Thanks!
Chandra