The Seiko 8420-6939 is a watch model based on the 8420 movement.
Parts List
| SA6N20SN00 | crystal |
| 25M02NA4 | crown - crown |
| 25M02NS4 | crown - crown |
| 0G1500N01 | case back gasket |
| 0Z0034B01 | case back gasket - crown and stem gasket |
Caliber 8420
Seiko 8420-6939 Watch Guide