Calling any BC experts- 6538 8mm crown / stem thread question..

Hi VRF-

I am wondering if anyone has an answer for me regarding the correct thread/tap size for my 8mm crown. The crown is for a 6538 with a 1030 movement. I have searched the VRF archive on this matter, and have read that there are 2 versions of the 8mm crown. The older ones take a bigger stem thread, and the later service ones take the smaller standardized thread. My 8mm crown is NOS, but not in the packaging, so I am not sure how old it is. I took a loose 1530 stem that I had and screwed on correctly to a 7mm triplock crown. This 1530 stem was too small for my 8mm crown. My question is, which stem do I need? Either the #6946 .9mm, or the #6947 1.10mm version.

Any info is greatly appreciated.
Thanks!
Glenn