In 76 they changed covers so the stator inserts between the covers and you only see about 1/4 ridge of the stator. Stator and rotor changed. Rotor is longer
I can't tell when it was actually the revised alt design but not sure if it was on 70s. I allways thought that but it seem it was more into the 80s. Anyway, as I mentioned The Beck Arnley 78 amps alt I bought quite ago got the rotor damaged and used the old squareback alt rotod I had to replace it. Side by side couldn't note any physical difference... even both measured something like 5 ohms. And it was my running alt for many years later untill I found a NOS Mopar alt at an old Mopar shop in Venezuela, revised design SUPPOSELLY 100 amps ( per a decal it had ). I bought two alts in fact. One is storaged.
sure I changed the pulley for the smaller one