I bought a 05 GMC Canyon w/33000 miles. It was not long before I found it had a bad vibration at 60 mph, was told it was tires so put top of the line Toyo's and vibration got worse. Power Chev. in Siblimity said it was tires so back to tire dealer where they rebalanced them and put truck up on rack to check for bad wheel or out of round but found nothing. Back to dealer, service manager happens to live close to me so suggested he drive it to work for a few days. 3 days later he calls and tells us it is a problem with this suspension and the fix is --150+lbs of weight between wheel wells and tail gate. Amazingly the vibration all but disappeared. There is a bulletin from GMC on this.