Help with determining correct crown size.

[Bandjgray]

I've been trying to locate the correct crown for my seamaster calendar 2867-4.
It's an unusual reference with a 38mm case and I'm having a difficult time determining the correct crown size. I believe it's a clover crown but that's as much as I can tell. My guess is around 5.3mm but I don't really know.
The crown that's currently on it is 4.8mm and doesn't appear to be correct.

 

[GuiltyGear]

According to this list, it's crown reference ST42023. This eBay listing measures it at 5.9mm: https://www.ebay.com/itm/142721851575