Here is some interesting reading from the parts manual. The first one is from 1929-1942, the other is from 1929-1949. The later ones were sold with no holes and cut to length.
Attachments
bed irons 1929 - 1949.jpg (266.45 KB, 83 downloads)
Bed irons 1929 to 1942.jpg (302.77 KB, 82 downloads)
bed irons, job numbers page 1.jpg (382.52 KB, 83 downloads)
bed irons, job numbers page 2.jpg (277.47 KB, 83 downloads)