Messerschmitt Bf.109G, German users, part three

In September 1942 a new version of the Bf.109G appeared, the Bf.109G-4, which looked similar to the G-2 in almost every respect, including performance, except for the fact that it was fitted with the FuG 16 VHF radio set, which provided clearer radio transmissions and had three times the range of previous HF radio sets. That change could only be distinguished externally by the position of the fuselage antenna lead-in which was moved further aft to between frames seven and eight on the fuselage spine.
As this version was havier than its predecessors, larger mainwheels were introduced and undercarriage wheels were altered so their vertical axis was nearly upright, rather than being parallel, with the oleo leg. Therefore, a teardrop-shaped fairing had to be made to the upper wing surface above the wheel-wells to accommodate the upper part of the mainwheels. This system was oftenly retrofitted to the G-2 version. Additionally a larger tailwheel replaced the original one and, as it didn't fit the recess, the retraction mechanism was disconnected and the tailwheel was fixed down. Until July 1943 1242 G-2 were manufactured with only additional four of them being made at Györ, in Hungary and WNF in Vienna.
Later on, between January and February 1943, a pressurized version, the G-3 was also produced which was similar to the earlier G-1 but it was equipped with the same radiot set as the G-4 and only 50 of them were built.
The G-4 saw many sub-variants such as a recon version, named G-4/R2 which was fitted with underfuselage cameras, a long-range reconnaissance version, named G-4/R3 which was fitted with underfuselage cameras and two underwing drop tanks, a tropicalized version, named G-4/Trop which featured sand filters in the engine air intake. There were two further variants, called G-4/U3 which was a high altittude reconnaissance fighter and another one called G-4/y which was a command fighter.

Sources:
1. https://en.wikipedia.org/wiki/Messerschmitt_Bf_109_variants#Bf_109G
2. Salamander Books - The Complete Book of Fighters