Fits for Paccar PX-6, PX-8, 1989 & Newer Cummins 4BT 3.9L, ISC 8.3L, B Series 5.9L, ISB, ISL 5.9L 6.7L, QSB 5.9L 6.7L and ISL9 L9 9.0L, Works on seal number 5259499 and 3926126. Make sure that the installation depth of crankshaft oil seal is correct.