Assuming you are referring to the axle, the 2000 Chevy Silverado 1500 has a 8.6 or 9.5 ring gear size with either 1.3 or 1.5 pinion shaft diameter. The 8.6 ring gear is found on trucks equipped with the 4.8L, 5.3L and 6.0L engines while the 9.5 ring gear is reserved for trucks powered by the 8.1L engine