I already posted about the variety of vehicles that fought on the Eastern Front way past their obsolescence, and here are some more that show up in a table listing available vehicles on the Leningrad Front for September 27th, 1941.
The first column of each unit lists vehicles that are fully repaired, the second lists vehicles that are subject to minor repairs. The last two columns tally up the vehicles for both categories among all units, and the bottom row totals up the total amount of vehicles for the unit (armoured cars in the numerator, tanks in the denominator). The units listed are as follows: 123rd Tank Brigade, 124th, Tank Brigade, 42nd Army, 55th Army, 23rd Army, 115th Infantry Division, 8th Army, 21st NKVD Division, and Front Reserves. The vehicles listed are KV, T-34, T-28, BT-7, BT-5, BT-2, T-50, T-26, flamethrower tanks (likely T-26 modifications), BA-10 and BA-20 armoured cars.
Given the proximity of Kirov factory, the amount of KV tanks available for combat is not surprising, and neither is the amount of T-34s being overshadowed by older vehicles, like the BT series and T-26es. Six entire T-50s defend the northern capital, but I don't know if the Kirov prototype is one of them, or is not listed due to being owned by the factory instead of a military unit.
The previous article also mentions the 124th Tank Brigade, but about 13 months later, allowing us to track some of the more interesting vehicles. For instance, right now it has zero BT-2s, but two of the Front's 19 BT-2s can be found among its ranks in a year. Only two of the 51 KV tanks remain, replaced with other obsolete vehicles that migrate among the Front's units.