He was 67 years old at the time of his death.
https://www.findagrave.com/memorial/48619810
Profile dates (William was born in 1892. He passed away in 1956) make him 64, so one of them must be incorrect.
Agree with Deb
. U.S., Social Security Applications and Claims Index, 1936-2007 [database on-line]. Provo, UT, USA: Ancestry.com Operations, Inc., 2015.