The 37 and 38 bumpers are not the same period .The rear bumper for 37 has a much greater curve that the 38 .the arms are shorter at about 8/9 inches. the hole distance is 16 inches .the bumper end is curved down refered to as a frown. The 38 is shorter with less curve ,longer arms at12 inches with hole distance at 13 inches . the frown is up referred as smile the bumperetts are also different to fit the bumper shape when they are turned over The 38 front and rears are the same but with different front arms . We are restoring a 38 and have been looking for a 38 ,they are hard to find .We have a real good 37 rear bought by mistake for a 38 it has also the arms should you need one . hope this helps need more infor .come back Johnny.