Originally Posted by thesoundguru

You said you found the transmission check plug in the cup holder. Did you check the trans level. This isn't just a oh it's good check. You need to cycle through each gear and for each gear add fluid. If you have not done this you have no info to tell if the truck has fluid in the trans. this is the place to start. if you have done this and have a full level then we can talk more advanced diagnosis.

Originally Posted by Extinct

Are you sure the trans is full of fluid? If it will move in reverse but not forward it is likely not a torque converter issue, more likely a trans solenoid issue, or possibly a front clutch. Where are you located?