The contact owns a 2019 Lincoln Navigator. The contact stated that while shifting the transmission from Reverse (R) to Drive (D), the driver's seat belt suddenly jolted her back into the seat, causing neck and shoulder pain. The Supplemental Restraint System (SRS) message was displayed. A loud, gunshot-like sound was heard, and an odor similar to a deployed air bag was noticed following the incident. The contact was informed by an unknown dealer that the parts were backordered for NHTSA Campaign Number: 26V344000 (Seat Belts). The contact then notified the manufacturer by telephone regarding the incident. The failure mileage was approximately 100,000.