Engine Number(s)

Sarah (nb Warrior blog) recently posted about some recently acquired injectors http://nbwarrior.blogspot.com/2008/03/if-youre-going-to-mug-me.html

Amongs't the ramblings of an excited woman ;-) she bought up the subject of the number(s) stamped on them (check out the comments).

Well, my injectors are all stamped with:
5mm
NATIONAL
56214
No1

6mm
NATIONAL
56214
No2

4mm
NATIONAL
53514
No4

56214 is my engine number, so:

Two of the original injectors for No's 1 & 2 cylinders and a replacement for No 3 (of off engine number 53514?). So where is engine number 53514 (was it a 4 cylinder?), and who's got my injector for No 3 cylinder?

So, there I am - out in the garage doing guess what? - cleaning, wire brushing, painting!

This time its the rocker covers. And guess what - on the flat machine end of the cover is stamped 56214 -1. Before you can say "boo to a goose", the remaining 5 have the machined ends cleaned up. Each are stamped 56214 - 1, 56214 - 2 & 56214 - 3. Three for the inlet and three for the exhaust.

I don't think you can see it very well in the photos, but its on the 'flat bits' at the front of each one.

Why did National take the time to stamp up individual components with the engine number and sub numbers for each of the cylinders? Surely a rocker cover is a rocker cover? It wouldn't be individually machined and made to measure for each cylinder etc - or would it?.

The only other place I know that the engine number is stamped is on the block at the flywheel end

So - where else is it going to turn up?

Edited to add - Jim, put your spanners down. Don't let Sarah make you take it apart, "just to see". ;-)