That is a great find, well done! Below is info I copied from another post by Jim Fisher, with a breakdown of the K-32 production variations.

HI
the numbers I have used over the years is below. Davids numbers are pretty close but I broke it down a little farther.
k-32 Narrow rib est. 400
k-32 Wide rib est. 2030
K-32 4 screw est. 400
K-32-2 est. 300
k-32-3 est. 500

The reason for the numbers is how many you see.
the -2 is the hardest to find
the Narrow rib and the 4 screw are the next hardest to find
and the 16-3 was made the longest.
and the 5 screw wide rib is the one yoy see the most of.
Jim Fisher
just my 2 cents worth.

__________________
Ken