After getting my hands on one of those pins, finding out it doesn't fit my Cadet, and doing a bunch of research and talking to an old timey dealer here's the findings:
That piece is used after serial number 678912. It seems IH made a production change at that serial number. Prior to that part num IH-144650-C2 was used. After that part num 703-0176 was used. Compare the two pins below and you'll see IH went to a heavier, thicker pin. I have also posted a photo of how the original pin interferes with my liftbar. So, apparently later production and repro bars are made to fit the later pin design which leaves me with my original problem, how to eliminate the interference with that bloody pin, either cut down the end of the bar or have a special pin made. Time for a beer.
