Welcome to the board. You got a pic of this thing? Lol. The adjustment nut is to adjust the clutch pedal for wear on the clutch friction surface. If the pedal is stiff, look for binding or kinks in the pedal. These can go bad sometimes when dirt gets in the cable, as well as a possibility of fraying. It can on the other hand have a heavy duty clutch assembly with a heavy pressure plate. I would replace the pedal and if it's the same, then it's because of the pressure plate. How hard would you rate it? It could be that it's just harder then what your used to in a truck or car since you said you just got the truck.