The Soviet standard design practice usually mandated fully shuttered engines in order to cope with temperature extremes. A slightly shorter span was incorporated, but many of the other alterations were less evident. The passenger door was moved to the right or starboard side of the fuselage, with a top-opening cargo door on the left or port side in place of the original passenger door. The structural reinforcement included slightly heavier skins, because the metric skin gauges were not exact equivalents of the American alloy sheet metal. Standard Soviet metric hardware was different and the various steel substructures such as engine mounts and landing gear, wheels, and tires were also quite different from the original design. Later modifications allowed the provision of ski landing gear in order to operate in remote and Arctic regions. The first PS-84s had begun to emerge from the GAZ-84 production line by 1939.