Name: John D. Macdonald
SSN: 562-10-xxxx
Last Residence: 91343 North Hills, Los Angeles, California
Born: 3 Apr 1904
Died: 28 Oct 1997
State (Year) SSN issued: California (Before 1951)
I don't know much at all about the geography of LA, but I did find info that suggests that Sepulveda is not a place (i.e. Sepulveda, CA) so much as a street, and that it is one border of the North Hills neighborhood.
Using that name, I find:
Nova Scotia, Canada, Births, 1836-1910 Record
Birth, Marriage & Death
Name: John Duncan MacDonald
Birth: 3 Apr 1904 in St.Joseph's, Antigonish, Nova Scotia, Canada
That leads here:
https://familysearch.org/pal:/MM9.1.1/JV9B-HBC
to Father's Name: Alex A Mcdonald
Mother's Name: Maggie Mcisaac
This page:
https://www.novascotiagenealogy.com/ItemView.aspx?ImageFile=1904-92404423&Event=birth&ID=184218
is his application to register his birth, made in 1943, when he was living on Wilshire Blvd in LA... confirms Alex and Maggie as his parents.
Then I can't find him again. *sigh*
This is NOT the same as John D(an) McDonald, born Jan 1904 in Antigonish, to Alex and Christina. I found a few records for this man before I realized it was someone else; this person lived in Michigan for a time, so far as I can tell.
There are more than a few McDonalds out of that same city, many with similar names. I found a John Duncan McDonald, same birth town, about a generation older who relocated to and died in Massachusetts, also.
I'll keep looking...