Erik;

I don't have a big problem using Nylock nuts. A (First use) Nylock nut is every bit as secure as castlelated nut in combination with a cotter pins...it's just that it takes a bit more faith to believe in the more modern Nylocks...I know what you mean...it's tough to argue with a cotter pin...you can see it, and put your finger on it...

...heat is a definate no-no for Nylocks though. Under the melting point of the nylon, it will still encourage the nylon to "cold-flow", undoing the whole principle by which they work (binding with the freshly cut threads in the nylon), over the melting point of the nylon, and you're back to essencially a normal, non-secured nut.

The way I keep the threaded ends of the steering rods from spinning during tightening is to clean and degrease both conical surfaces before installation. I find that preped this way, by just seating them together with nothing more than hand-force, there is enough binding between the two pieces to prevent spinning...maybe just a little tappy-tappy with a soft hammer.

...I do strongly advise using an open-end or box-end wrench, which will allow you to verify that the pin is not spinning (not for instance a socket).

Cheers