The Seiko 8420-5550 is a watch model based on the 8420 movement.
Parts List
| SA6N70SN00 | crystal |
| 25M02NE3 | crown - crown |
| 0G1700N01 | case back gasket |
| PK12Z | band - leather band |
| A100BS | others - push pin (for mb) |
| 07R03CTH | others - hour hand |
| 07R03CTM | others - minute hand |
| DZ0041B01 | others - crown and stem gasket |
Caliber 8420
