Been doing some reading on this, 880 PzIVF2/G were made in 1942. Subtract out 125 for Op. Blau & about a hundred delivered to DAK until 1/43, that makes 655 probably delivered in grey to units in AG North, Center, and France rebuilding. The AG North & Center units definitely known to have taken them in summer/fall 1942 deliveries are Panzer Divs 1, 2, 5, 12, 18, 19, & 20. In addition, the 11PD was transferred to AG Center after Blau began and took PzIVG replacements later which would have been in grey. The GrossD was transferred to AG Center too after Blau began, but I'm not sure if they took later replacements, so theirs may have been in funky Blau camo (same goes for 9th PD).
The reason for the late year buildup in AG Center was because Hitler wanted to smooth off his line & wipe out the Soviet 10th & 16th Armies near Kirov in August, codenamed Op. Wirbelwind. Konev & Zhukov's Rzhev attack in August foiled his plan, but the southern pincer arm did manage to take Ulyanovo. A few months later Zhukov launched the much more powerful Op. Mars. So with these actions, and the two major operations in 2nd half 1942 to break the Leningrad blockade, grey PzIVG tanks saw plenty of action. Not many pics to document it however, because all eyes were on Stalingrad & with the exception of the breaking of the Leningrad blockade, the results of all these actions were bloody & embarrassing for both sides. The Germans were embarrassed for being taken by surprise yet again, but at Rzhev, and not once, but twice(!), and the Russians for not achieving their objectives in Mars or pre-Mars in August.
