Awww, nuts. (No pun intended. ) The reason for putting the cotter pin back in is to prevent the castle nut from falling off and causing an accident. Here's is another possibility, which has worked for me, though not for this front end part. Back the nut off one turn. Start the engine and run the steering wheel through several full turns, left to right. If that does not do it, drive the truck forward and backward slowly in the driveway while also turning the steering wheel.
If that won't work, a specialized kind of puller that looks sort of like a pitman arm puller may be needed. A puller called a pickle fork might work, but might also damage the tie rod end. A two-jaw gear puller might work, but the pivoted jaws are likely to slip off.