In June of 1942, Ausf L tank entered production. 653 were produced by Daimler-Benz, MAN, Alkett, Henschel, Wegmann, MNH and MIAG until December of 1942 (chassis numbers 74101-75500). Ausf L was armed with 50mm KwK 39 L/60 gun and two 7.92 mm MG 34 machine guns. Externally it was almost identical to late model Ausf J as it was developed by modifying it. The main difference was new torsion bar gun counter balance, which replaced the original the coil spring gun recoil mechanism. Armor protection of the front turret was increased from 30 mm to 57 mm and 20 mm spaced armor was installed on the superstructure front and in many cases on the gun mantlet. The design of the vehicle was simplified as rear deck was modified (air-intakes and hatches) and early in production hull escape hatches, loader’s vision port on the mantlet and turret side ports were removed. Ausf L was also mounted with new special system to transfer heated engine coolant from one vehicle to another. Single Ausf L was mounted with an experimental 75/55 mm tapered-bore KwK0725 gun and was designated as PzKpfw III Ausf L mit Waffe 0725. Vehicles send to North Africa were equipped with additional air filters, modified oil filters different cooling fan reduction ratio and were designated as Ausf L(Tp). Ausf L was also first to be mounted with anti-aircraft machine gun mount (Fliegerbeschussgerat 41/42) on commander’s cupola. This became standard on al new PzKpfw III tanks and was mounted on older models during service. Many were mounted with 5 mm hull and turret armor skirts (Schurzen).
From October of 1942 to February of 1943, 250 new Ausf M (10-serie) tanks were produced by Wegmann, MIAG, MAN and MNH (chassis numbers 76101-77800). Ausf M was late production model Ausf L mounted with new wading equipment allowing wading up to depth of approximately 1.3 m, in contrast to previous 0.8-0.9 m. This led to all air inlets and outlets as well as other openings and joints being sealed, while modified muffler with closure-valve was installed high on the hull rear. The new system was developed and modified version used in Tauchpanzer III submersible wading tanks. The hull rear mounted rack of five smoke generators was replaced by three 90mm NbK dischargers mounted forward on both sides of the turret. Ausf M just as Ausf L was armed with 50mm KwK 39 L/60 gun and two 7.92 mm MG 34 machine guns. Vehicles produced in 1943 were factory mounted with 5mm hull and turret armor skirts (Schurzen). Large number of Ausf M was converted to either Sturmgeschütz III or Ausf N.


From February of 1943 to April of 1943, 100 Ausf M tanks produced by MIAG in Braunsweig (chassis numbers 77609-77708) were converted by Wegmann in Kassel to Flammpanzer – flame-thrower tanks. New vehicles were designated as PzKpfw III (Fl) / Sd.Kfz 141/3. They were also commonly known as Flammpanzer III or Panzerflammwagen III. It was unmodified Ausf M tank with additional 30 mm to 50 mm armor plates welded on for protection to the hull front. This was done, as Flammpanzer III tanks had to get closer to their targets being vulnerable to enemy fire. In contrast to regular tanks, it was operated by three men crew composed of commander/flame gunner, radio operator/hull gunner and driver. The main gun and internal ammunition stowage were replaced with the flame-thrower and fuel tanks. This vehicle was armed with 14 mm Flammenwerfer flame-thrower and two 7.92 mm MG 34 machine guns. The flame-thrower was mounted in place of the original 50 mm gun and concealed in a thick 1.5 m long pipe made to appear as standard armament. The flame-thrower could lowered 8 degrees and raised 20 degrees. Each vehicle carried some 1020 liters of inflammable oil (Flammol) in two tanks inside the vehicle. Oil was pumped into the pipe by Koebe pump driven by two-stroke DKW engine and was ignited by an electric charge (Smitskerzen). The supply of oil allowed some 125 one second or some 80 to 81 two to three seconds long bursts. The maximum range of the flame-thrower was 60 m using ignited oil and 50 m using cold oil. The range also depended on the weather conditions.