5mmx0.9x14mm metric hex nut. Used on pre-1968 Toyota Land Cruiser 40 Series in various places, such as the ammeter post.
Diameter: 5mm
Pitch: 0.9 extra coarse thread
Wrench size: 9mm
Yellow zinc finish
Retired JIS Specification. Specification in use today is M5x0.8, with 8mm wrench size.