An initial order of 759 were placed on January 1939.
Starting in 1941 additional 30 mm plates were bolted to the upper and lower nose-plates.
A turret basket was fitted for first time in this model series. Rear plate on the turret was made one piece and this eliminated bulge below commander's hatch.
The tracks were widened to distribute the extra weight. New sprockets, idler wheels, and reshaped shock absorbers were added. The 1st return roller was moved a little forward to help distribute the heavier track's weight better.
The turret was redesigned to accommodate the 50 mm KwK 38 L/42. Some of the late production vehicles had a 50 mm L/60 installed.