Savoia-Marchetti chief designer Alessandro Marchetti (1884–1966) retained the general configuration of the S.73 but introduced retractable main landing gear to reduce aerodynamic drag.

It was powered by three Alfa Romeo 128 RC.21 engines and had a greater cargo capacity than the SM.75, and entered military service as the Savoia-Marchetti SM.82.

The SM.75 GA (for Grande Autonomia, meaning "Long Range") was a modification of the SM.75 powered by three 641 kW (860 hp) Alfa Romeo 128 engines and fitted with a powerful radio and auxiliary fuel tanks to boost the aircraft's range to 7,000 km (4,300 mi) with a 1,100 kg (2,400 lb) load.

With a four- or five-man crew and a 200 kg (440 lb) load, the SM.75 GA had a range of 8,005 km (4,974 mi) at 298 km/h (185 mph) while flying at altitudes between 3,500 and 5,000 m (11,500 and 16,400 ft).

After Italy entered World War II in June 1940, the Regia Aeronautica needed aircraft to maintain contact with Italian East Africa, which was surrounded by British-controlled territories.

In January 1942, the commander-in-chief of the Regia Aeronautica, General Rino Corso Fougier, began planning a Rome-to-Tokyo flight.

An SM.75 was selected for the flight and was modified into the first long-range SM.75 GA.[4] The first mission of the SM.75 GA was to drop propaganda leaflets saying "Italian colonists, Rome is not forgetting you.

After 10 hours and 20 minutes, they arrived over Asmara (Eritrea) and released leaflets, but instead of continuing on to Benghazi in Italian Libya as planned, they returned to Rome.

[4] Starting from Guidonia Montecelio on 29 June 1942, the SM.75 GA RT landed later that day at Zaporizhzhia, 2,030 km (1,260 mi) away in occupied Ukraine, the closest airfield to Japanese held territory.

Maps of Soviet positions were inaccurate, and they had to climb to 5,000 m (16,000 ft) to avoid interception, consuming their oxygen supply faster than planned.

With fuel running low, they landed at Pao Tow Chien in Japanese-occupied Inner Mongolia on 1 July 1942, 6,000 km (3,700 mi) east of Zaporizhzhia.

It took off on 18 July 1942 from Pao Tow Chien, retraced its route, and, after 29 hours and 25 minutes in the air and having covered 6,350 kilometres (3,950 mi), it landed at Odessa in Ukraine before continuing on to Guidonia Montecelio.

Initially flying at low altitude, they climbed to 3,000 m (9,800 ft) but having burned too much fuel one diverted to bomb Port Sudan instead.

All but one of the bombs were successfully dropped before returning to Rhodes the next morning after having covered 6,600 km (4,100 mi) in 24 hours and 15 minutes.

After Hungary entered World War II, these aircraft were pressed into service with the Magyar Királyi Honvéd Légierő (MKHL), Hungarian Air Force.