I can tell you this about that hard to get to cotter pin. Getting mad at it, throwing tools, nor cussing loud enough for the impressionable young neighbor kids to hear clearly won't get it out. I have clearly proven that.
Endeavor to persevere is where you need to start, then listen to what Kevin suggested.

1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission