The series production saw the introduction of the more powerful T750 motors, which boosted the power to , while the bogies were upgraded for . The frontal part was improved and made more aerodynamic. A characteristic livery with two blue stripes on a pale grey background was adopted. The first 50 units proved successful, and the Ferrovie dello Stato (FS) ordered 60 more to be built starting from 1972. 16 units were adapted for feeding at 1.5 kV DC. During 1974 two locomotives (units 056 and 057) were provided with a "shunt chopper" system (later the modifications applied were rolled back, making the two units identical to standard once again), while in 1975 the E.444.005 adopted a "full chopper" electronic system, which was later also adopted on the E.632/633 classes, and which granted a peak power.