Everything has power when i turn the key to the on position but when i turn the key to start the truck, nothing happens. headlights dont dim or anything and everything still has power. all fuses are good. I have put 2 new starters on it and neither starter fixed the problem. Put a new neutral safety switch and a new ignition switch on it and it still wont crank or move at all. It starts no problem when i push it and kick start it. 1993 isuzu rodeo, V6, 4 wheel drive, 202K miles, standard transmission

Have a look at this:
http://www.fixya.com/cars/r5605161-trouble_shooting_isuzu_starter

Check if you getting power to the single wire on the starter when you turn key to start position.If power is not there then starter is not a problem , I'm not sure if this car has a starter relay , but you may want to check that too.

When you crank the engine are you getting a full 12 volts positive at the solenoid switch on the top of the starter?

Have you got a full 12 volts negative to the switch?

Also, check the earthing strap from chassis to engine is good.

Regards

Lloyd