Help needed with identification of a vintag Girard-Perregaux watch

[peterki]

Hi to everebody,

I have just bought a stainless steel vintage GP. I would appreciate any help in indetifying this model (year of manufacture, model, caliber etc.). I cannot unfortunately open the back for the movement number and also the Internet search made me no wiser. On the back, the number reads 9180 FH. I would guess the watch was
made in late 60s-70s. It is a manual, hand wound watch which keeps excellent time.