When was your Armada manufactured? I've got an 05 LE that was built in July 05. I've seen posts that all trucks built after 5/05 should have been manufactured WITH the new brakes, but I'm a skeptic. I've got 1200 miles now and I'm just gonna watch what happens...
Brakes - Add Me To The Growing List
Well as somewhat predicted my relatively new 05 Armada SE 4X4 Smoke rolled up easily to around 3700 miles and the dreaded brake shudder, judder, shake began. The billowing clouds of black brake dust had started from mile Number 1. Prior to purchase the master tech I've been using for both my Nissan's had warned about the brake issues and said that if I bought one and it was not quite up to par upgrade wise he would get it resolved. Fortunately at the 3750 service interval, I took it in and they replaced the front rotors, resurfaced the rear rotors and put on all new pads on all four corners. Brakes feel good so far. Too early to tell on brake dust. 
