Does this seat have a built in seat belt retractor? My 2004 Silverado has this design (the seat belt pulls out of a small tower built into the top of the backrest) and I feel that it is a poorly designed system. I don't think that the seat belt should ever be incorporated into the seat.
If your seat has this design, it may be part of a massive seat belt retractor recall that GM had a couple of years ago. Since this is a safety related recall, there may be no time or ownership restrictions.
I found a reference to a recall designed to fix this problem: "Front seat belt bunching, replace retractor assembly 1999 Silverado, Sierra."
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And this:
"1999 Chevrolet Silverado LT from North America. Several recalls including seat belts and brakes."
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