16710 serial numbers for 3185 or 3186 movement?

[blue lion]

I have a Z60xxxx serial number 16710. I did research here and other sites to determine if it is known when Rolex switched from the 3185 to 3186 movement.
Websites say the 3186 started in the "late Z" serials but I've been that number be 6xxxxx, 7xxxxx, and up from there.
I did the wiggle test-no wiggle. Did the crown test, it went 5 hours in one crown revolution. So that didn't clear anything up but I'm assuming I have a 3185.
I don't have a tool to open the caseback.
Thanks.

[Alpino]

.

You have a 3185 , no doubt to have if as you have noticed "crown test, it went 5 hours in one crown revolution" .

Transition was around z8xxxxx , but there have been exceptions to that "rules". It's because Rolex uses the cases they have in stock when time comes to assemble a watch. This stock can be constituted with many serial number at the same time.


I have already seen 16710 with 3186 and s/n z5786xx , z724xxx , z7753xx , but those are exceptions.

On another hand, I have never seen 16710 with 3185 with a s/n > to z82xxxx

[toolr]

I had a coke bezel 16710 with 3186 and stick font dial, the serial number was a very late "Z", Z969XXX. Foolishly sold it, didn't get a lot of wrist time.