Thanks for all of the tips! I put some liquid wrench on the bolt and let it set for a few minutes and tried again. It turned but... it just turns (doesnt come out). I'm thinking at this point something is wrong. I thought this was going to be simple.
Any ideas on what my next step should be?
Well,ordinarily I wouldn't say anything but this is the second time you have referred to it as a "bolt" ;it's not a bolt ,it's a castellated NUT.
Thus it won't come "out ", but it should come "off ".
It should be simple as you say.
So, it hasen't moved any at ALL? (laterally?) It wouldn't re-tighten if it's "stripped". ??????????
I can't believe it's stripped and the only thing keeping things together was a cotter pin and rust....