Second step from first end is splined
A shaft having two or more different diameters (greater than 0.031 inches (0.79 millimeter)) along its length. It must have one or more of the following conditions: a specified surface finish designation in the range 1 to 125 microinches (0.025 to 3.2 micrometers) arithmetical average (aa), machined peripheral flat(s), circular groove(s), keyway(s), splines, threads, or holes. The ends and/or shoulders may be machined to accommodate bearings, couplings, and the like. It is not designed for use in aligning by fitting into corresponding holes of another item. For items used to support rotating members see axle(1), shouldered. For items not having any of the above conditions see pin, shoulder, headless. Excludes shaft(1), straight; and axle(1), straight.
Classification: Transmission shafts and cranks, except camshafts and crankshafts
NSN 5910-01-410-7749
NSN 5915-01-384-4464
NSN 5920-00-786-0112
NSN 6320-01-194-1253
NSN 6240-01-265-6958
NSN 6685-00-453-3584
NSN 6645-00-900-5830
NSN 6650-01-624-9222
NSN 6130-00-233-6427
NSN 6150-00-379-4656
NSN 5855-01-006-1827
NSN 5930-00-536-3989