Boeing ISFD / Airbus IESI / Airbus ISIS

[SQWave]

I am working on a flight simulation version of the Thales standby attitude indicator, which is used in various aircraft with slight modifications.
It is used in Boeing aircraft, Airbus airliners and helicopters, and more. We already got a prototype running in a simulator, but we're now trying to improve the prototype for production.
The real unit has a light sensor, which I would love to add to make it just a little bit more accurate.

This questions is somewhat of an 'investigation/search' I guess.
I have included 3 images, one of a black IESI from a helicopter, in which you see the sensor in the red square.
Ideally I would use the exact same sensor, but of course this information is not available.
The window is about 5x5 mm, it fits in there. It looks like it is a 3 legged component. Most probably a phototransistor?

Does anyone have any idea of which component this might be? I know that it is a long shot, but maybe I'm luck
If I cannot find it, then I will use something 'generic'.
In any case, thank you all in advance for your suggestions.

[SQWave]

By the way, I already had a suspect
https://ie.rs-online.com/web/p/phototransistors/1685320

But maybe someone has a better suggestion or can confirm my suggestion.