A number in the 400s that is actually NOT metric.....
Wonder what that fits??
All my studs are 610-037, 610-085, 610-135...etc...
All #s in the zeroes, and 100s !!!!!!
All for from the 1930s - to - about 1972 !!!!!!
Of course at 75¢ each, you won't cry if they don't work... That's for sure...