In Italy in the 1930's there was a need for new vehicles for government sponsored excursions and inter-city express services. The ALn 772 was then developed, with the abbreviation for “Automotrice Leggera a nafta”, standing for “Light Diesel Railcar”. Thanks to modern construction and electrical welding technology, the twin-engine vehicle with 72 seats had an unladen weight of just 37 tonnes.

At each end was a driver's cab with an upright six-cylinder diesel manufactured under license from Saurer. They each had a displacement of 14.3 liters and each produced 150 hp. The engines were spring-mounted in the car body to reduce interior noise and vibration. Since the bogies did not have to accommodate the motors, as was the case with other railcars of the time, cheaper, older designs of bogeys could be used. The power was transmitted via a hydrostatic gear box and allowed a top speed of 130 km/h.

The production should initially take place at the Officine Meccaniche in Milan. Due to initial difficulties with the new production methods and limited capacities, half of the first lot of 200 vehicles was handed over to Fiat. Production was halted during World War II due to other priorities, but later resumed thanks to the Marshall Plan. By 1957, a total of 327 vehicles had been built for Italian customers, including some smaller, private ones in addition to the FS.

Some of the vehicles reached average speeds of over 100 km/h while on duty. They only faced competition from new railcars in the 1960s. In the 1970s, the service increasingly shifted to branch lines. From 1981 onwards, the inspection deadlines gradually expired, so that the vehicles were retired by 1986. Only very few examples have survived today, which is due to the execution of the noise insulation for the passenger compartment. Since large amounts of asbestos fibers were used for this purpose, health hazards arose as the material aged, which made restoration possible only with considerable effort.

After the war, Poland urgently needed new vehicles for passenger transport. Since the ALn 772 had similarities with the pre-war Luxtorpeda, the idea was to procure some of these railcars. Although Poland had too little foreign exchange, it did have high-quality coal. Since Italy hardly had any high-quality coal for the efficient operation of steam locomotives, an agreement was reached on the delivery of three ALn 772 in exchange for coal. Poland analyzed the vehicles delivered in 1951 and made replicas as the SD80. For a longer period of time, they performed their duties in express service and were converted into SR70 railway service vehicles from 1967 onwards.