2001 GMC C1500 Front end shakes and wobbles

I have a 2001 GMC Z71 extended cab truck with appx 120000 miles. The steering has begun to feel lose and now at low speeds there is a shaking feeling from the front of the truck up through the steering wheel. I have checked the tire pressure, tire condition, and tire balance weights....all seem to be fine. The shaking also happens at high speed just not as bad. The shaking is not bad enough yet to stop driving the truck but is a cause of concern