Hi again Arnaud. Removal of the air filter box could give a clearer view of the area of interest though you might be able to see what's what with your new endoscope attachment for your mobile phone - or maybe a small mirror and some light might suffice. I'm not a V6 person as I mentioned previously and I have no personal experience of the engine but I would guess that the 2 black plastic covers either side of the throttle body house the engine's rear timing belts. If that is so then the engine number it would appear from the pics that I've seen is located in the area below the cover that is nearest to the front end of the car and that it is on the engine facing the gearbox. A few more pics from the site above might help:
Pic1 Pic2 Pic3 Pic4