Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number R191 found under Brake Drum by Rosco Mfg Co. The National Stock Number assigned to this part is 2530003758809, and the Federal Supply Class is 2530 Vehicular Brake Steering Axle Wheel And Track Components. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like R191.