sound like you have "grabbing" brakes to me. i would check them for contamination and if they are then you will need new brakes and to replace all rubber components, and if your brakes are not contaminted i would start checking wheel bearings, warped rotor or drum, and the balance of your tires. i would check your rotor or drum first, that is most likely the cause
The 2006 GMC Sierra-1500 has 12 valves.
The 2006 GMC Sierra-2500HD has a V8 engine.
The 2006 GMC Sierra-2500HD has 16 valves.
The 2006 GMC Sierra-2500HD has overhead valves (OHV).
The 2006 GMC Sierra-1500 has overhead valves (OHV).
The 2006 GMC Sierra-2500HD has a 5-speed manual.
The 2006 GMC Sierra-2500HD is a gas-powered vehicle.
The 2006 GMC Sierra-1500 has a 5-speed manual.
The 2006 GMC Sierra-1500 is a gas-powered vehicle.
The 2006 GMC Sierra-1500 is 17 ft. 1.7 in. (205.7 in.) long.
The 2006 GMC Sierra-2500HD is 18 ft. 8.5 in. (224.5 in.) long.
The height of the 2006 GMC Sierra-2500HD is 6 ft. 4.2 in. (76.2 in.).