The Envoy XL has been assigned 531 TSBs over 4 model years.
TSBs contain recommended steps and procedures for diagnosing or repairing a known problem. They are issued directly by GMC to service technicians. You'll often see TSBs used as evidence in lawsuits when owners feel the automaker should help with repairs.
A TSB can cover multiple models and years. The 2006 Envoy XL has been involved in the most campaigns with 485 total service bulletins.