As Rick posted, buy a kit, piece by piece will cost more and you won't get many of the needed small brackets, fittings, and fasteners needed to do the job correctly.
Google air ride GMC, GM, or Chevrolet and you can start your search there. Theres so many companies making these kits you would be hard pressed to list them all.
As far as a specific type or mfgr for the bags I always prefer Firestone air spring bags, durable, and reliable.
Also think about why your buying an air ride suspension, competition hopping, ride height, towing/weight control, or ride comfort, the reason is each type use requires different compressors, lines, valves, switches, suspension links, storage tanks, etc, not all systems are comparable with all uses.
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