I found this over on some hot rodders forum while surfing. It is a long post and if this information can be found elswhere on this forum and I missed it please feel free to delete. But I thought this was worth posting as this list decodes most of the GM codes you will find on your build sheet.   These GM build sheet numbers decode as follows:   AG7 6 way Power Seat AK1 Custom Deluxe Seat Belts AL5 Deluxe Rear Center Seat Belt '67. AN7 Strato-Bucket Seats, Swing out! Al3 Power