The bodies aren't completely the same. For sure the pilots are completely different, with the 2-rail one affixed to the body. I don't know if it would be a matter of just removing the front coupler from the 3-rail chassis to accomodate the 2-rail shell, or it would take more than that. Of course, the area around the rear coupler will be different as well. I know from experience that sometimes these hurtles can be challenging. Converting an Atlas 8000 gal. tankcar from two rail to three rail turned out to be a real task, as I found out! Sounded like it would be simple, but it wasn't!