Draw-Tite website only goes back to 63. 55 on up have a 34" frame width, which is pretty universal as far as the hitches go. 54 and earlier half tons have a frame that is tapered from front to rear, and is about 46 inches wide in the rear. Some level of modification generally needs to be done to come up with a suitable hitch. You may try to find the widest hitch you can, and cut it down to fit as needed.
John
