I see. I have found the same pic but of a better qulity. It can be noticed that both the fuselage cross and the one on the undersides were of the late type. The pic was taken over Russia in 1942. According to a couple of sources including the soviets ones it was the C-1 varinat of the Stroch. IMHO the top markings were of the same type these seen in the pic. Usually these on tops were slightly smaller than those on undersides.
Here is a screenshot o fthe decal markings of the ABT Decals set. I would say these are correct in the cross size.
the pic source: the net.
The C variant of the Fi 156 was introduced on assembling lines in 1939 with the pre-production C-0 sub-type. The production of the C-1 started in 1939/1940. So the late German LW markings are almost sure.
Fi 156 C-0: Pre-production. Essentially a "flexible" version of the A model. (produced in 1939)
Fi 156 C-1: Three-seat liaison version. (produced in 1939–1940)
Fi 156 C-2: Two-seat observation type, which had a raised, fully glazed rear dorsal gun position for mounting a MG 15 machine gun for defense. (produced in 1940)
Fi 156 C-3: Replaced the C-1 and C-2 with a "universal cockpit" suited for any role. (produced in 1940–1941)
Fi 156 C-3/Trop: Version adapted for tropical and desert conditions. Filtered intakes. (produced in 1940–1942)
Fi 156 C-5: Addition of a belly hardpoint for a camera pod or jettisionable auxiliary tanks. Some were fitted with skis, rather than wheels, for operation on snow. (produced in 1941–1945)