A 21mm adapter is required to fit our upgraded 175 amp alternator into all cars originally fitted with a 90A alternator: i.e. all 3.2 Carrera models and later 930/911 Turbo (1984 - 1989). 

This listing is for the 11mm adapter only.  Must be fitted with a 10mm adapter to make a total of 21mm.     Adapters are NOT required for 964 alternators.

Contact us with any questions.