In looking at the front spring mount for the rear wheels / differential / rear axle / it was apparent that it was considerably more complicated than the other (unscrew the nut) mounts. Not being familiar with this sort of mount or fastening method, we looked at it and finally came to the conclusion that the pin was driven into the mount, through the spring and retained by another threaded pin. This was NOT completely obvious, as the retaining pin was camouflaged by grit, grease, dirt and detritus, besides being a half inch down in a hole. The clue was a screw slot, revealed after cleaning the hole out. But the screw wouldn’t budge. Applications of Kroil penetrant, were without success, so out came the “heat wrench” propane torch. We heated and lubed several times and then re-lubed with more Kroil.
Finally the screw loosened a bit. More Kroil. Half turn out. Half turn in. Repeat. Full turn out. Full turn in. Repeat. Eventually the screw came out. That’s nice. There was no way to bang the actual shackle pin out. The threads looked like and felt like 3/8 x 24 fine thread, but a bolt threaded in got very tight and started to strip.
Time to call on someone that may have actually done this operation — Mike Howard (another Model K owner). On the evening of May 12, we got a call from Mike. He suggested a slide hammer and a gear puller arrangement. Good news. We were on the correct path to extracting this pin.
On May 13, Dad & I got another (unstripped) 3/8 x 24 fine bolt and an all thread connector nut at the hardware store and welded up a tool for the end of my slide hammer. BINGO! A few hard smacks and the pin gave up and let loose. The rear end was now detached from the frame.