Firewalkerd1,
The problem you are having is because pushrods that are commercially manufactured are actually pressed into the metal and not cut. You'll never be able to cut your own threads on the rod. Your best bet is going to use a threaded rod and solder a threaded connector to the opposite end of the rod. Make sure that you put a lock nut on the rod so that it can't vibrate and rotate out of your ball links.

Here is the link to what you need at Tower Hobbies.

[link]http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXD887&P=0[/link]

Hope this helps.

Ken