Abstract: A pin box assembly comprising a towing vehicle portion comprising a frame, a towed vehicle portion comprising a frame having a proximal end and a distal end, a torsion resistant pivot portion disposed between the towing vehicle portion and the towed vehicle portion, the torsion resistant pivot portion disposed at a distal end of the towed vehicle portion, the torsion resistant pivot portion comprising, a bar disposed within a tube, the tube fixedly connected to the towing vehicle portion and the bar fixedly connected to the towed vehicle portion, at least one resilient member disposed between the bar and the tube, the resilient member compressible between the bar and the tube upon a relative rotation of the tube with respect to the bar, an air spring disposed between the towing vehicle portion and the towed vehicle portion, the air spring disposed toward the proximal end of the towed vehicle portion with respect to the distal end, and a hitch pin connected to the towing vehicle portion for engaging a hitch on