The casting number and part number are often the same, differences of a single or few more intergers occur where the casting is part of a sub assembly, for example a piston supplied with rings and pin, or a cylinder head only supplied ex factory complete with valves.
Plunger brake pedal has a spline to locate on the pivot lever, the bearing surface for this is a frame lug and when the lug wears it is not a simple bolt on replacement. That's progress.
Swarfy