Help Page for Ancestry Links This is the page that can help.
There was also a G2G Answer that mentioned APID formatting that is not covered in that Help page.
Also, US Social Security Claims Index is on family search
There is a US Social Security Death Index
Thanks for your replies. That was the WikiTree help page that I was studying, but my particular Ancestry link wasn't matching up to any of the examples. Jim got me sorted out.
I've double checked and my grandfather wasn't in the SSDI. He lived and died in Taiwan, although he visited the US for some extended periods once he had grandchildren here.
I tried to find the SS Claims Index on FamilySearch and came up empty handed. This FS page directs people to Ancestry.
Thanks again for taking time to reply; I'm still learning my way around how to source in WikiTree.
Yes! The distance from Taipei to New York was vast, so the memories I have of my grandfather are extra special. :-)