Looks as if yours is also flyback
On the movement, am I right reading 'seventeen 17 jewels Girard Perregaux & Co unadjusted' (all upper case)? Mine has just one additional line below that reads 'Swiss'.
May I ask you to check whether the movement bears the same inscriptions as mine at the bottom of your picture, i.e. below the balance. From right to left mine reads as follows: GP monogram/ '720' (cal. 720)/ Valjoux' monogram.
Judging from your picture the GP monograms on the case back are similar on both watches, perlage is bit less clear on yours but that might due to the relative lack of sharpness of your picture, the inscription below the monogram is inverted on mine, as it reads Acier inoxydable Swiss, as usual, all in upper case. Btw mine is also protected by a dust cover.
I hope that it will be possible for you to check this. In advance, thank you.