2003 GMC Sierra 1500 Pickup Owner's Manual - Page 28

Q: What's wrong with this? You can be s,..ously injured if you wea. ,he shoulder belt under your arm. In a crash, your body would move too far forward, which would increase the chance of head and neck injury. Also, the belt would apply too much force to the ribs, which aren't as strong as shoulder bones. You could also severely injure internal organs like your liver or spleen. A: The shoulder belt is worn under the arm. It should be worn over the shoulder at all times. 1-21