Just to share from Jan's message, I have requested SS5 forms twice. The first one was for my grandfather, Jacob Levine, when trying to find who his parents, my g-grandparents, were. It was very helpful and broke open SOME of that brick wall.
The second one was for one of his sisters, Helen Levine Denison, because I haven't been able to find her birth info in Poland. Unfortunately, that SS5 didn't provide me with any info, because although she came to the US in 1906, when she was 6 years old, on the form, she put that she was born in the US...
However, I share this because this form can be VERY helpful!
LEVINE/LEWIN, SILBERNAGEL/SILVER, EPSTEJN, MOCZYDLOWER/MOCHEDLOVER, ERLICH, GRUNPELTZ, JOSKOWICZ, ZYLBERSZTEJN, ABRAHAMOWICZ