I have coached the 3-3, 3-4 and 4-2-5 defenses but I have never coached a true 4-3 scheme. I am going to research the 4-3 and write a blog post that contains my findings. You can be sure it will be simple, sound and easy to teach. If you have any 4-3 material that would be helpful please email me at email@example.com or firstname.lastname@example.org. Thank you for reading this post and God bless!