Found this while researching Pz III for my HL to Tamiya conversion once its released

"Some of the later Panzer III variants were fitted with turret mounted storage bins (Gepack Kasten). Very common were the canister racks mounted on the turret and/or at the rear of the hull. During early stages of Operation Barbarossa in 1941, Panzer IIIs were equipped with single-axle trailers carrying extra fuel in order to increase their radius of operation. During production, PzKpfw III's design underwent many changes including various modifications made on the turret (e.g. cupola, gun mantlet, vision slots, hatches, armor skirts) and hull (e.g. escape hatch, armor skirts) and superstructure (e.g. air intakes, spaced armor, headlights arrangement) components. Since mid 1943, Panzer IIIs were mounted with Schurzen - 5mm armor skirts. During service and repairs, many Panzer III tanks were up-armored, rearmed and re-equipped with new equipment and components creating completely non-standard variants. Vehicles send to North Africa were equipped with additional air filters and different cooling fan reduction ratio. They were designated as (Tp), Tp being short for Tropisch / Trop / Tropen - tropica"

Source http://www.achtungpanzer.com/pz8.htm Jan 6 ,2007 16:45 ET