Dear toura,
I understand that the following Tu-4 models appeared.
Tu-4: standard bomber version.
Tu-4D: modified Tu-4 as troop carrier (28 troops) and with fuselage doors for paradroppings. The Tu-4D also had large containers on underwing pylons carrying some of the troops` equipment/weapons. The Tu-4D retained the long-range bomber capabilities. Seems up to 300 Tu-4 aircraft were modified as Tu-4D.
Tu-4K: Experimental Tu-4 used as launch plane for the piloted Raduga K Analog aerodynamic testbed and for the KS-1 Kometa (later AS-1 Kennel) large early cruise missile. The Tu-4K had two underwing pylons to carry the K Analog and/or KS-1.
Tu-4LL: Up to 6 modified Tu-4s for use as testbed (flying laboratory). Used to test engines such as the Kuznetsov NK-12 turboprop, Lyulka AL-5, AL-7, Mikulin AM-3 and AM-5 turbojets etc.
Tu-4N: Modified Tu-4 for use as aerial tanker and tested with various types of refuelling systems.
Tu-4R: Tu-4 modified for strategic recconnaisance. Forward and aft bombays modified for extra fuel or recce equipment. Possibly the Tu-4R was also built as new aircraft.
Tu-4T: Experimental Tu-4 modified for 44-52 troops. Flew in 1956, but development halted.
Tu-4UShS: Tu-4 modified as (crew) trainer. Usually all operational equipment was removed.
KJ-1: Developed in PRC. Re-engined with turbine engines and at least one was seen with large dorsal radar disc.
Hope the above will help. Regards Walter