2005 GMC Sierra 1500 Pickup Owner's Manual - Page 32

Lap Belt When you sit in a center rear seat position of an extended cab or in the center front seat position of a crew cab, an extended cab, or a regular cab, you have a lap belt. To make the belt shorter, pull its free end as shown until the belt is snug. Buckle, position and release it the same way as the lap part of a lap-shoulder belt. If the belt is not long enough, see Safety Belt Extender on page 1-32. Your lap safety belt has no retractor. To make the belt longer, tilt the latch plate and pull it along the belt. Make sure the release button on the buckle is positioned so you would be able to unbuckle the safety belt quickly if you ever had to. 1-26