In 1936, Chapelon began the rebuild of a PO 6000 class 2-10-0 as a 2-12-0, with two high-pressure cylinders between the 2nd and 3rd coupled axles mounted behind four low-pressure cylinders. That unusual cylinder arrangement was required due to the loading gauge being too narrow to accommodate two low-pressure cylinders with the required volume to fully expand the low-pressure steam. There was also an additional level of "superheat" between the high- and low-pressure cylinders, allowing the loco to achieve a tractive effort of 83700 lb.