Description Hydraulic pump shaft oil seal. I.D. 0.9350", O.D. 2.004", W. 0.5315". Tractors: NAA, 600, 700, 800, 900, 2000, 4000 series (1953-1964). Can replace NCA851A, D8NN851AA. This item is a suitable alternative for the following: C5NN851A, D8NN851AA, NCA851A