Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number D974A1 found under Link Roller Chain by Insinger Machine Company The. The National Stock Number assigned to this part is 3020002318718, and the Federal Supply Class is 3020 Gear Pulley Sprocket And Transmission Chain. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like D974A1.