Yeah I tried the SSDI...Nothing.
I think my best bet now is to zero in on their property. Just prior to his death May and Fred purchased a house in Berwyn (for $3000). The Cook County Recorder of Deeds maintains a Grantee/Grantor index, so maybe I can come up with something when Widow May eventually sold the property.
Of course, the Recorder of Deeds Office only has the records that far back at their downtown facility and they don't do anything by mail or phone. Have to do your research in person. Downtown Chicago! Talk about traffic!! Oh well....
Take care-
Paul