464 has inside admission piston valves. The valve chests are outside the center line of the cylinders. The first piston valve conversions were made to line up with the valve rod from the Stephenson Valve Gear. When Walschaert's Valve Gear was applied to these locomotive a bell crank or rocker was used to get the motion from the outside valve gear to the inside leaning piston valves. There was a pivot cast into the motion bracket for these locomotives. On the later conversions they used the same cast motion bracket, just torching off the pivot.