I guess it would depend on what type you intend to use. Most of the mounting hardware is going to be different so keep that in mind. GM made a first generation internally regulated unit in the early '70's and the were a popular choice with hot rodders of the day because they were an easy install. Problem was that the voltage regulator inside the unit was a POS. It was easily fried by jump starting the car or if there was a loose connection for a battery cable or the hot lead to the alternator. The later units were upgraded and were much better protected. That having been said, Taking apart the whole alternator to replace a dead regulator is still a PIA.
Dave