My truck with NP203 started making loud clicking noises (not a clunk), and it turned out to be the u-joints (rusted, roller bearings had metal in metal) and the centering yoke in the front driveshaft CV joint.
The CV joint has a spring-loaded centering yoke in between the u-joints, and it keeps the joint parts in alignment as the driveshaft turns. It can wear down, spring can break, etc, and then the joint does not turn smoothly. It did not feel loose when installed, but the damage was very clear when I took it apart.
IIRC, I got the new sealed u-joints and the centering yoke from RockAuto because it was the cheapest source. Easy job to disassemble and replace parts once I got the driveshaft off.