The DB-3F is more widely known as the Il-4. It was the most heavily used Soviet bomber during World War II. It began series production in 1940. Post-War NATO refered to this aircraft as
Bob. Just over 5,000 of the Il-4 had been built when production ceased in 1944.
The DB-3 series started in 1936. The DB-3M was an improved version, mainly made up of superior build techniques. The DB-3F (Il-4) had quite a few changes, increased gunner armour and improved protection (Upgraded guns to 12.7mm UBT) along with new 1,100 hp M-88 [replacing the old 950 hp M-87B] engines. The DB-3F was renamed the Il-4 sometime in 1942.
It could carry 2,500 kg of bombs internally, and on short missions would carry another 1000 kg externally.
The PS-84, aka. Li-2, is the Soviet conversion of the DC-3. It was basically the same aircraft but with a turret in the top mounting a 12.7mm UBT - I think.
These aircraft would have been in direct support of the coming Soviet offensive that relieved Leningrad and pushed the Wehrmacht over the Oder river, in January 1945.
Do you have information on where on the Ost Front these kills were made? Because the Red Army was marching through Romania and Bulgaria in December 1944 ... and these could also have been in aid of that advance.