He probably said governor when he was actually talking about the high idle screw. That's the only thing you can screw all the way in.
Does the engine start without your foot on the throttle? When governor springs are tightened too much, the idle goes up. When you lower the idle setting to compensate, the truck may idle fine, but won't start until you give it a little throttle.
I would just idle it up as mentioned above. If you don't have starting problems, I doubt the governor was adjusted.
If you really want to check into the governor, Hemi gives some good advice. If you don't have a set of calipers, I'd recommend removing the shut off solenoid linkage on the side of the pump and opening the 7/8" plug. Rotate the engine over until one of the governor nuts is visible. Check the stud protrusion. Rotate the engine 360° and check the other set. They need to have the same preload.
With this method, you can actually put your finger on the stud and 'feel' it.
Warning: You will lose a little oil when you open the plug, so be ready!
Good luck.
-Chris