This is a realistic Proto48 drop in replacement bolster for the old style AtlasO 70T Roller Bearing truck (Item 7034.) To use this bolster requires a little ingenuity, since there really is no correct Proto48 axle to use. The axles from NWSL have issue, but at least are long enough. I have designed this to use the Protocraft roller bearing axles ... the problem is, that these only come with 36" wheels and this truck requires 33" wheels. What I did was remove the wheels from a set of 100 ton axles and a set of 70 ton axles and I swapped the wheels. This can be done easily if you have a drill press of something similar. Otherwise, it isn't so easy. The NWSL 33" Atlas P48 axles will work, but require a lathe to turn the axle shaft down to an appropriate diameter. So, pick your poison.