If you're looking for the 9x13x0.5mm copper crush washer, the forum host has them available. I've used them on an 81 240D with an MW pump, exact fit. My delivery valves are the 'copper washer only' style, no o-rings involved, so maybe these aren't right for an earlier MW pump. But if the size measures 9x13x0.5mm, it should work. The copper isn't anything special as best I can tell, but the size is unusual.

https://www.pelicanparts.com/More_Info/0049974540.htm?pn=004-997-45-40-M14&fs=0