8709 Air Spring, Replaces Hendrickson Trailer (Intraax AA230) S21800 & Firestone W01-358-8709 Many people are searching the Internet for the Hendrickson numbers S21800 or C21800. These two numbers are interchangeable for the same air spring and the bag listed here is a high quality direct replacement Manufacturer: Load Boss Load Boss Bellows Number: LB8709 Goodyear Bellows Number: 566-26-3-073 Goodyear Part Number: 1R13-159 Firestone Bellows Number: 1T17CA-5 Firestone Part Number: W01-358-8709 Replaces: Hendrickson Trailer S-21800 (Intraax AA230) Cross References: 1R13159, 1T17CA5, 566263103, 8751, C21800, 8460, C20900, S21800, 1R13159, W013588709, W01 358 8709, 1R13-159, W01-358-8709, 64645, 10 10.5-15 P 460, 1010.5-15P460, 1010.515P460, S21800, AS87090