The seat belts locked up in my truck.
The GM seat belts of your generation vehicle have widespread problems with the seat belt ratcheting device. The seat belts have a safety feature which is designed to stop seat belt movement during emergency braking. The safety feature is however known to engage under normal driving conditions and lock the seatbelt into place. The seat belt usually can be unlocked by gently pulling on the seatbelt but at times the seatbelt safety feature completely jams internally. If the belt can not be unlocked by the standard procedure the seat belt device will need replacement.