 Your 1989 Alfa Spider could have one of two ignition rotors. Knowing which one your car has is important, since they are completely different and do not interchange with one another.
Most of the 1989 cars use the same rotor as the 1982-1988 cars. The distributor shaft in these cars is 14.25mm. The correct IAP part number is 1100. But, according to the Alfa Romeo microfiche, some of the 1989 cars were equipped with a "glue on" rotor that’s just like the one used on the Motronic-equipped cars from 1990-1994. The distributor shaft in these cars is 10mm in diameter. The correct IAP part number is 29507. | 
