Can I cook tofu pups that I purchased several months ago and whose sell by date was Oct 28,2008?

I am thinking of cooking tofu pups for the first time and I brought the packet around 5 months ago and threw it into the freezer and conveniently forgot about it.Today i took it out and saw that its sell by date was Oct 2008. Is it safe to use since I did not open it and it was in the freezer?