Hi there. I would suggest looking through salvage yards for that air bag pocket, they will be in 1997-2000 3/4-ton and 1-ton GM trucks. You might also luck out and find one on the forums.
Check out GMT400 - The Ultimate 88-98 GM Truck Forum , that forum is dedicated to just the 88-00 GM trucks, lots of great info there.
Check out GMT400 - The Ultimate 88-98 GM Truck Forum , that forum is dedicated to just the 88-00 GM trucks, lots of great info there.