The Seiko 8420-5580 is a watch model based on the 8420 movement.
Parts List
| RE2N20SN00 | crystal |
| 26M02EE3 | crown |
| 0G1700N01 | case back gasket |
| WI051 | others - other band |
| WI052 | others - other band |
| 04R05DHH | others - hour hand |
| 04R05DHM | others - minute hand |
| 04R08E1H | others - hour hand |
| DZ0041B01 | others - crown and stem gasket |
| 04R09DHH | others - hour hand |
| 04R09DHM | others - minute hand |
Caliber 8420
