[HFAlex]

Unfortunately i really don't know!
The only chance i have is to go to Macchi or Caproni factory, 20km from here....???

[char_aznable]

It seems that it wasn't applied on first series (including serie III), but retro-fitted along with armoured glass later. Anyway, from some images I've seen, it seems to be present on all aircrafts by 1942. 8)