One of the prototype features that has always been modeled incorrectly until now are the access panels covering the sander valves on the boiler. This early coal version model shows the original configuration for these panels and is representative of the way they looked on all versions in early service. The locking latches on the ends of the panels are functional. The other basic boiler detail has been reproduced as faithfully as possible, from the punched rivet detail and separately applied boiler lagging bands to the layered lagging on the upper firebox.