Re: Gearbox interchangeability ?
Yes you can convert an alfasud type gearbox with mechanical speedo drive to a 33 type with electronic speedo sensor by swapping the output flanges and the cable drive unit for the sensor.
BUT remember that the clearances in the diff are set by the odd shaped shims between the output shaft flanges and the gearbox case. So you really should pull the gearbox apart and check the diff clearances with a dial gauge, fit the correct thickness shims, and reassemble. If you don't, chances are your gearbox will start making bad noises after a while and then you'll need a new one.