The body of the second model, which was the three-axle prototype of the Star 66, was mounted on a longitudinal welded frame made of pressed sheet metal.

The reason for this decision was the impossibility of simultaneous production of two models, caused by the technical and financial limitations of the Polish automotive industry at that time.

After a positive opinion was issued by a commission of the Ministry of National Defence, in January 1956 the technical documentation of the serial versions was approved and work began to prepare the factory in Starachowice for the production of this model.

The vehicle body, similarly to the prototype versions, was mounted on a welded longitudinal frame made of pressed sheet metal.

The running gear featured a front rigid drive axle suspended on semi-elliptical leaf springs, additionally supported by two hydraulic arm shock absorbers.

The drive unit was coupled to a 5-speed manual, non-synchronized gearbox, connected via a tubular shaft to a mechanically controlled two-speed reducer.