The wheels on the steering axle and the drive axle look like what one would normally find on a 450 series GMC. Drag axles were added by cutting the back spring hanger off and hanging the equalizer on the spring. Neway was the most popular drag axle and it used a 20k trailer axle. I have never seen a drag axle like this one with a square axle. I would say that that it is some odd ball axle and the hubs fit it and nothing else. C&H is active in the salvage business, but many of the old vehicles have been sitting around for years and the people who knew a little about them have retired. This one may be a newer addition because it doesn't have trees growing through it yet.