This was posted over on the Dawgman.com boards (big thanks to iqueral for originally posting these), and the links are too good not to pass along here too.
We all expect that new DC Justin Wilcox will implement more odd-numbered fronts here, and in anticipation of that, here are some good primers on understanding a 3-4 defense and that means in terms of roles and responsibilities for the various positions and how it compares to the 4-3:Comparing the base 4-3 and 3-4 defenses:
The X's and O's of the 3-4:
Understanding the lingo of gaps and DL positions (i.e. 1-technique, 3-technique, etc):
Diving deeper into the varieties of 4-3 and 3-4 defenses ("over" vs. "under", etc):
As we start counting the days until Spring Practices, this should provide some good reading material as we start thinking about our defense under Wilcox and which pieces should fit best where.