The "48" is not the car number. It signifies that it can hold a container up to 48 feet in length. These are Gunderson stack well cars from Des Plaines Hobbies. They are nicely detailed and hold Des Plaines Hobbies 48-ft containers seen in the pictures. The J.B. Hunt is a Des Plaines Hobbies 53-ft container that does not fit into these 48-ft cars but can be double-stacked prototypically on a 48-ft container as Mark has done. This summer Des Plaines Hobbies is planning to introduce the Gunderson Maxi-IV 3-car articulated stack well car that will carry their 53-ft containers in the well. This series of S scale cars (I'm using the word scale to mean 1/64th scale because Des Plaines offers them in either high-rail or "scale" wheelsets) is part of their S Scale America line.