New Zealand Datsun Club

Hey all, anyone have an idea as to what this stamped number refers to?
It is on the radiator support panel. I assumed it was the chassis number but I'm lost as to why there is an m at the front of it...

normally means the colour of your car ( paint code )

p.s have you a build thread ?

Ah, that would make sense. I was lime green lol
Tbagg is what the thread is named under