The two swashplate pumps in my workshop are numbered 5P2 No1010 and 5P2 No1095, and Colin Heath’s is 5P2 No1027. I think that they probably started at number 1000. The numerals 2 are both in Roman numerals, but I don’t know how to type in Roman numerals on my laptop ! Seems a bit quirky/archaic…
Scratched onto the dial on both of the ones here is 35848/32, and both have the magnesium type manifold . Presumably the number scratched onto both dials means something, but I haven’t a clue unless it is a part number, with the last two numbers standing for 1932 ?