xbox 360 bug fixx

does anybody remember back when the 360 had a bug problem that caused the 3 red lights..well surprisingly my 360 made it this far and i jsut got the 3 red lights.. but the problem is that i got it in the very beginning of february 06, so it might be right before or right after they started putting the new 360s out..does anybody know when they styarted producing the 360s that were fixed? because im seeing that if they will still fix the release 360s for free