Select model catalog: 8.1L-6081HFN03 Natural Gas Engine (Waterloo) PC8401 8.1L - 6081HFN01 Natural Gas Engine (Waterloo) PC2502 8.1L-6081HFN02 Natural Gas Engine (Waterloo) PC8400 8.1L-6081HFN04 Natural Gas Engine (Waterloo) PC8402