Hi, Scott:

You're quite welcome. This might be your Sylvester in 1880 with his parents and siblings:

Series: T9 Roll: 1148 Page: 340
1880 - Slocum, Luzerne Co., PA - 6/24/1880
Dull, Henry - 35 - head - married - farmer - cannot read/cannot write
-- Matilda E. - 30 - married - wife - house domestic
-- Stella C. - 8 - dau.
-- Horace H. - 6 - son
-- Sylvester J. - 3 - son
PA/PA/PA for all.

And if that's your Sylvester, here's his parents in 1870:

Series: M593 Roll: 1363 Page: 653
1870 - Emaus P.O., Upper Saucon Twp., Lehigh Co., PA - 10/8/1870
Seiffert, Frederick - 64 - farmer - $4,000/2,000
-- Catherine - 60 - keeping house
Doll, Henry 25 - turner - married in May
-- Matilda - 21 - keeping house - married in May
Weiss, Mary - 12
PA for all.

Good luck with your search!

Debra