I'm not certain there would be any real records related to John. This is one of the few estates I have during the early 1930s where the deceased was someone who would have paid into Social Security and would have had a mother (no children) as an heir. John was working for a trucking company in Quincy, Illinois, at the time of his death in 1937.
I am not certain just how much information there would be in these records or how helpful they would be in this case. We'll post an update if warranted.