Most prethreaded push rods have rolled threads, the actual unthreaded portion is too small to thread, if you run a nut onto the threads, you will see that it will actually go past the threads then slide down the metal. As RC Ken said, buy a solder clevis or just a solder on threaded brass thread sold for that purpose. I used to have some mild steel rod that I customed threaded but the brass threads work just fine and much less work.

Randy