Two things - First, how I got the old thermostat out - Picture #1
- you were right!! The 41mm thermostat has exactly the same thread as the 45mm. Further, although the 45mm has seemingly slightly larger inlet cutouts, the thermal slug is SMALLER in diameter - making it most likely exactly the same coolant flow...
50 years from now - how are we going to restore a "classic" microprocessor based modern car?? Alfas - 1980 Spider, 1987 Milano, 1976 Spider