Gerald,
Allow me to correct myself. The Type Two Carriage was used for 24 pounder field howitzers and the 12 pounder Napoleon. Both having trunnions of 4.2 inches in diameter. The Type three Carriage was used for the 20 pounder Parrott, the 32 pounder field howitzer, and the 1841 Model 12 pounder gun. These having trunnions of 4.62 inches in diameter. The trunnions on tubes carried by the Type One Carriage as I listed previously were 3.67 inches in diameter. As the diameter of the tube increased and the size of the trail (center stock beam) increased, the cheeks had to increase in heigth to accommodate the tube. Thus the center line of the trunnions on the various field artillery pieces would not be aligned at the same distance from the ground.

Keith