First picture would be what came on a 47 model. Swing drawbar pivot and pin is pictured like the one only used on very early tractors though. Pivot casting had to be unbolted from the transmission to remove the swing pin on those. Later ones had the little plate show in the picture that could be removed to let pin out the bottom of the casting. Also real early tractors used longer angle brackets and support rods. Probably in 1940 and earlier tractors going on my memory. Picture with the roller is the last type attachment IH sold as replacement parts for a M tractor. Swinging drawbar anchor was changed. Both the U and swing drawbar was made thicker. Roller used on the swing drawbar. Rollers also had a change along the way with the mounting hole location for the roller. Different hardness of the drawbar metals and fine threads sometimes were used on the angle bracket attaching eye bolts were changes since 1947. U and swing drawbars in real good condition are kind of hard to find.