Torque Tube coupler Pin Questions

[19Fordy]

Still working on my rear end so I can install the special oil seal to prevent rear end gear oil from running down inside the torque tube. I heated the head of the pin to cheery red and proceeded to hammer it to form a head as there was no head formed back in 1940. Let it cool down and quickly discovered (with a smooth file) that the end of the pin had become as hard as glass. Could not center punch it or drill it. Plus the pin now had a head but had become loose. Chiseled (chipped) top of it away and was able to drive the pin out. The pin measures .251 in. dia.
I wonder if that pin was made of air hardened tool steel and why did it loosen?

QUESTIONS:
1. Where is the best place to purchase two new pins?
2. Any special procedure to follow when installing the new pin
and forming the head?
THANK YOU.