In the mid-1960s, UTB signed a licensing agreement to manufacture Fiat tractors, which got underway in 1970. Initially, a large portion of the parts were imported from Italy, but gradually the tractors became entirely Romanian. At that time, the tractors were visually identical to the Fiats.

In 1974, a new model series 445/500/550 was introduced, featuring partially synchronized transmissions. Depending on the version, there were 6+2, 8+2, 9+3, or 12+3 gears, with the latter two including a relatively fast crawling gear range. The 550 model had a dual clutch. Like the Fiats, four-wheel-drive DT models were offered. Alongside these were corresponding crawler tractor models and the 445 HCP, which had adjustable ground clearance ranging from 127 to 161 cm. In some countries, the model 400 was marketed as a power-restricted version of the 445. The 600, in turn, was a parallel model to the 640.

In many countries, the cab used was the British Duncan. However, Sweden soon switched to a domestic cab, with a reported noise level of 81.5 dB. At the end of the 1970s, a more powerful 640 model was introduced, whose four-wheel-drive version featured hydrostatic steering. In 1981, the series was supplemented by a 3-cylinder 530 (50 hp).

The technical specifications correspond to the models sold in Sweden and Germany. More powerful parallel models were also sold under the same model numbers: 445/45 hp, 500/54 hp, and 550/55 hp.

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