After the Famulus, tractor production in the GDR was revamped. The goal was to offer tractors in five different size categories. The smallest class was filled by the work machine carrier GT 124. A 3-cylinder TT 220 was developed for the 45-horsepower power class, the ZT 300 for the 90-horsepower class, and the ZT 400 for the 160-horsepower class. The largest size category was left for a later time. The TT 220 and ZT 300 were developed to the point of serial production readiness, but ultimately only the ZT 300 was put into production, which began in the autumn of 1967. The manufacturer was Traktorenwerk Schönebeck and the engine was made by Motorenwerk Nordhausen. The 6.6-liter 4-cylinder engine was developed based on the IFA W50 truck engine. The direct injection technology was licensed from MAN.

Also adapted from the IFA truck was the driven front axle, which was installed in the four-wheel-drive model ZT 303 introduced in 1971. The transmission in the ZT tractors consisted of three basic gears, three ranges forward and two backward, as well as a crawler gear. In total, there were 18+12 gears. The steering was power-assisted and the brakes were hydraulic drum brakes. The cab was modern even by Western standards. However, the pedals came through the floor and the gear levers were in the center. The strengths of the ZT included ease of maintenance and good gear ratios. Weaknesses were low ground clearance and a large turning circle. The weight was also quite high.

In 1973, the factory merged into the Fortschritt combine, and later the Fortschritt brand also appeared on the sides of the tractors. Initially, the ZT was either red or blue in color; in the later years, there were also Fortschritt green versions. The cab was always white. Around the mid-1970s, the steering was changed to hydrostatic. In the spring of 1978, the engine power was increased to 100 horsepower. ZT tractors were sold in Western Europe, at least in France, Belgium, and Spain. Approximately 70,000 units of the model series were produced.

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