Did you try searching the forum for info?
I know stuff like that has been discussed here in the past.
Whether it was that specific model, well...
I never followed those threads too closely.
A google search, using your string, got quite a few hits.
"Scientific Atlanta D9476 64/128/256 QAM Modulator"
Not sure this 1-page PDF is of much help, though.
Here is a 3-page version.
Part number 567710 may be of some help in future searches on the SA web site.