This is a A-381703R1 Shaft, PTO Drive PN: 381703R1Main Description As Following : A-381703R1 Shaft, PTO Drive P.N: 381703R1 Spline: 16 , 1.680" Dia.Teeth: 22 Replaces: 381703R1-R IH Found in Section & Models : PTO Parts > PTO and Related Parts, Case-IH INDUSTRIAL/CONSTRUCTION: 2504 (Farmall SN 2470-14951 / IH SN 512-17589), Case-IH INDUSTRIAL/CONSTRUCTION: 2606 (Not Used On Tractors W/ Forward & Reverse, Case-IH INDUSTRIAL/CONSTRUCTION: 3616 (SN <998), Case-IH TRACTOR: 504 (Farmall SN 2470-14951 / IH SN 512-17589), Case-IH TRACTOR: 606 (Not Used On Tractors W/ Forward & Reverse Drive) Associated Items : New Also A-IH-O-2504-I, A-IH-O-3121, A-IH-P-3082, A-IH-P-5042504, A-SMIH201, A-IH-O-2606, A-IH-O-3121, A-IH-P-3082, A-IH-P-6062606, A-SMIH25, A-IH-O-3121, A-IH-O-3616, A-IH-P-3082, A-IH-P-3616LDR, A-IH-S-CLUTCH, A-IH-S-ENG460ETC, A-IH-C-MUSCLES, A-IH-O-BATTIGN, A-IH-O-504, A-IH-P-5042504 And : Spline: 16 , 1.680" Dia. Teeth: 22