I haven't played with it enough yet, but I'm guessing there is some sort of year cut off. I noted the following:
- Dorothy Ufkes, died September 2008--no number
- John Ufkes, died December 2003--no number
- Grace Johnson, died June 2000--number shown
- Ida Neill, died July 1994-number shown
- Tena Ufkes, died November 1986--number shown
- Cecil Neill, died December 1968--number shown
I'm guessing, based on my UNSCIENTIFIC sampling (these are my children's great and great-great-grandparents) that the "cutoff" is between June of 2000 and December 2003.
I'd do more experimenting, but other duties call.
But it appears that we are definitely seeing change in what information is being presented from the SSDI from the Ancestry.com family.