Seat back. For IH tractor models: Hydro 70, 86, 100, 504 Deluxe, 544 Row Crop, 544, 560, 574, 606, 656 Prior to S/N 14500, 666, 686, 706, 756, 766, 806 Prior to S/N 14500, 826, 856, 966, 1026, 1066, 1206, 1256, 1456D, 1466, 1468, 1566, 1568, 2504, 2544, 2656, 2706Deluxe, 2756, 4100, 4156, 4166, 4186 After S/N 19259. Replaces 387174R92