| Description | Part Number |
| 128MB DDR DRAM DIMM | 40X5937 |
| 256MB DDR DRAM DIMM | 40X5938 |
| 512MB DDR DRAM DIMM | 40X5939 |
| 550 Sheet Duo Drawer w/ 100-Sheet MPF, complete | 40X2284 |
| 100 Sheet MPF tray from 550-Sheet Duo Drawer | 40X5435 |
| 64MB Flash Card | 40X1455 |
| Autocompensator mechanism (ACM) standard tray | 40X5410 |
| Controller board, C544n, C544dn, C544dw | 40X5427 |
| Exit deflector and bin full sensor flag | 40X5433 |
| Front cover, C543dn, C544dn, C544n | 40X5430 |
| Fuser drive motor | 40X5415 |
| Fuser exit sensor | 40X5413 |
| Fuser plus ITU Maintenance Kit, 110V | 40X2254 |
| Fuser plus ITU Maintenance Kit, 220V | 40X2255 |
| Fuser, C540, C543, C544, 110-120V | 40X5437 |
| Fuser, C540, C543, C544, 220-240V | 40X5438 |
| High-voltage power supply | 40X5405 |
| Image transfer unit (ITU) | 40X5403 |
| ITU paper path thermistor | 40X5429 |
| Left cover | 40X5417 |
| Lower left frame and lower right frame w/ cable cover | 40X5422 |
| Low-voltage power supply (universal power supply) | 40X5409 |
| Main drive gear , with motors | 40X5412 |
| Operator panel (DBCS) and display | 40X5436 |
| Operator panel and display | 40X5431 |
| Operator panel bezel and name plates | 40X5432 |
| Photo sensor (one per package) | 40X5426 |
| Pick tires | 40X5168 |
| Printhead | 40X5411 |
| Right cover | 40X5416 |
| Toner cartridge contacts (Pogo pin) | 40X5421 |
| Toner density sensors, left or right (one in package) | 40X5414 |
| Toner meter cycle card | 40X5404 |
| Top cover | 40X5418 |
| Tray 250-sheet, C54x | 40X5419 |
| USB port and cable (for portable flash drive) | 40X5425 |
