You'll find a searchable database for CA death records from 1940 through 1987.
I put in your Aubrey Thomason and sure enough, he's in the database.It's interesting to compare the SSDI results and this CA Death Index.
The state of Illinois issued him his SS number - and his last known residence was Sunnyvale, CA as you said - as per the SSDI record.
However, per the CA Death Index - he was born in Arkansas and died in San Francisco, CA.
Here's the data from the CA Death Index:
Name:Thomason, Aubrey Benjamin Born:14 Nov 1915 in Arkansas Sex:male Mother's maid name:GRAY Died:16 Aug 1982 in San Francisco, CA - aged 66 yrs It also has his SS security number - that you already have
But - with this - you can now go for his death certificate in San Francisco - and maybe that obit you want will be easier to hunt down with the day of the month now vs just the month/year.
The combined SSDI and CA Death Index info give you some added flesh on the bones to see if he is indeed the one you're looking for.At the very least, you know this one was in Arkansas, Illinois and California!LOL
With the web addy above, you'll be able to find other folks who died in CA btw 1940 and 1987.