Sadly, I don't have the production figures on the 4 ATM.
There were several kind of bezels, Damien.
Here is one, but there was also a decimal one.
One word about the difference of treatment, which is in fact a guess I will have to check.
If I remember well the answer from the Heritage Gallery Team, to whom I asked this, they answered me that the Jaeger movements, on the Chronographs, were never signed, while the LeCoultre and Jaeger-LeCoultre Chronos were.
The 4 ATM was only produced by Jaeger, while the Diving Chrono was only made by LeCoultre and Jaeger-LeCoultre, hence the difference.
Best,
Nicolas