| Part No. |
Upgrade Tier | Core Positioning | Cross-Reference Parts | Compatible Engines | Key Applications |
| 3821575 |
Original OEM Benchmark | Factory original core prototype for Cummins NT855 oil pumps, official cross-reference benchmark for all same-spec products | 3821572, 3015273, 3045882, 3077770, 3609837 | NT855 Big Cam II/III/IV, Full NTA855 & NH855 Series | OEM replacement for HD trucks, buses, construction equip, gensets, marine power; fits early NT855 engines |
| 3015273 |
Mid-Term Optimized Upgrade | Factory upgraded model based on 3821575, optimized gear structure & oil flow, improved high-load durability; fully compatible with all same-spec models | 3821572, 3821575, 3045882, 3012728 | NT855 Big Cam III/IV, NTA855, NH855 | Replacement for high-load working conditions of heavy construction, large gensets, mining equipment; fits Big Cam III/IV engines |
| 3821572 |
Latest Universal Upgrade (Market Mainstream) | Final factory replacement for 3821575 & 3015273, optimized pump structure, heat dissipation & sealing, wider fitment; 100% compatible with all previous models | 3821575, 3015273, 3045882, 3077770, 3609837, 3821571 | NT855 Big Cam II/III/IV, Full NTA855 & NH855 Series | Universal replacement for HD trucks, buses, construction equip, gensets, marine power; the most popular model in the global aftermarket |
