When did Nissan start putting on the improved brakes?

Sometime in May, 2005. Don't let this prevent you from getting a good deal. If you find one pre May, they are under warranty and can be replaced for free if you have any problems. Many people don't. This was the only change I am aware of they made on later '05 models. ;)

Yes, I have a 2004 Armada with bad brakes. I've had the car 1 1/2 years and it has been back to Nissan for new brakes 9 times. They fix it free but it's a real pain to find the time to take it in and go back to get it.