Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 5R4991 found under Coupler Drawbar Ring by Caterpillar Inc. The National Stock Number assigned to this part is 2540012327128, and the Federal Supply Class is 2540 Vehicular Furniture And Accessories. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 5R4991.