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 6610-00-504-2839
NSN 5895-01-456-9358
NSN 6650-01-557-4143
NSN 5999-01-519-9353
NSN 5930-00-992-6725
NSN 5985-01-199-2582
NSN 5910-01-004-1615
NSN 6105-00-682-6969
NSN 6645-00-433-0695
NSN 5960-00-243-8397
NSN 5905-01-415-2902
NSN 5920-01-522-8211