[brummbaer]

On with the T-55, and things get tougher...
Btw, I'm leaving out elements irrilevant to the game, like external stowage boxes etc.

T-55 (Obj. 155) in production 6/1958-7/1962:
Based on T-54B and T-54M. 580hp V-55 engine and new transmission 155.08 sbB, max speed 50km/h; PAZ anti radiation equipment, automatic fire-fighting equipment "Rosa"; 100mm D-10T2S gun with STP-2 "Ciklon" two-plane stabiliser, 43 rounds, TSh2B-32P gunner sight, no AAMG, two SGMT mgs (one coax, one fixed in glacis, fired by driver), introduced BK-5M HEAT round with 390mm (Soviet) or 375mm (Yugo) penetration, side armor protection over engine compartment reduced to 70mm; smoke generator in the exhaust.
AAMG introduced back in 1969. KTD-1 LRF introduced in 1974. Neither of those two mods have any specific designation.

T-55K (1959)Additional R-112 radio, APU, no glacis MG, 37 rounds

TO-55 (1960)ATO-200 FT instead of coax with 12 shots supply of fuel, 25 main gun rounds, 750 rounds for glacis MG.

T-55A (Obj. 155A) 1962-1977:
Anti-neutron liner, no glacis MG, coax changed to PKT.
AAMG introduced back in 1970.
KTD-1 LRF introduced in 1974.

T-55AK (1962)
Additional R-112 radio, APU, 37 rounds

T-55AD (1983) T-55A equipped with 1030M "Drozd" APS
T-55AD-1 (1983) 1030M "Drozd" APS, V-46-5M engine.
Altogether 250 tanks for soviet naval infantry.

About 30.000 produced.
Poland built T-55 from 1958 to 1964 and T-55A from 1964 to 1977 for a total of 7000; command tanks AD1 (equivalent of K-1 for regiment commanders) and AD2 (eq. to K1 and K2 for for comapany and battalion commanders).
Czech built 3377 T-55, 3820 T-55A, 1280 T-55AK-1.
Rumenian versions are left aside for the moment.

Modernizations:

T-55M (1984) T-55 modernisation. "Volna" FCS, KDT-2 LRF, BV-55 ballistic computer, TShSM-32PV two-plane independently stabilised gunner sight, 2 planes gun stabilizer"Ciklon-M1" stabiliser, 9K116 "Bastion" missile system with 1K13 guidance sight, 12.7 AAMG, thermal shroud for gun, additional BDD armor for glacis and turret (380mm KE, 450mm HEAT), 10mm reinforced rubber side-skirts, additional 20mm armor under the drivers seat; V-55U engine with 620hp, new torsion bars; new radio R-173; SGD Type 902B Tucha 81mm.

T-55M1 No missile capability.
T-55M-1 (1984) with V-46-5M engine.
T-55M1-1 No missile capability, V-46-5M engine.
T-55M1K Command tank, no missile capability, APU, additional R-112 radio, 37 rounds
T-55M1K-1 same with V-46-5M engine.

T-55MV no additional BDD armor but K-1 ERA mounted
T-55M1V no missile capability
T-55MV-1 V-46-5M engine.
T-55M1V-1 V-46-5M engine.
T-55M1VK command version, analogue to T-55M1K
T-55M1VK-1 command version, analogue to T-55M1K-1.

T-55AM modernisation based on T-55A, same improvements as in T-55M
T-55AM1 no missile guidance
T-55AM-1 with V-46-5M engine.
T-55AM1-1 no missile capability, V-46-5M engine.
T-55AM1K command version, analogue to T-55M1K
T-55AM1K-1 command version, analogue to T-55M1K-1

T-55AMD Drozd APS, without additional BDD turret armor
T-55AMD-1 Drozd APS, without additional BDD turret armor, V-46-5M engine.
The same 250 tanks, if still all serviceable, of naval infantry.

T-55AMV no additional BDD armor but K-1 ERA mounted. Ukraine and Syria have upgraded to this standard.
T-55AM1V no missile capability
T-55AMV-1 V-46-5M engine.
T-55AM1V-1 no missile capability, V-46-5M engine.
T-55AM1VK command version analogue to T-55M1K
T-55AM1VK-1 command version analogue to T-55M1K-1.

T-55AM2B: Czech built T-55AMV with Kladivo FCS, LRF, meteorological sensor and Bastion ATGM. Adopted by CZ and DDR.
T-55AM2 same without Bastion ATGM.
T-55AM2PB USSR built for DDR (about 100?) and after reunification sold back to USSR, plus other transformed for russian army, Kladivo LRF, Bastion e K-1 ERA.

T-55AM2P: Polish buil T-55AMV con Bobrova LWR, Merida FCS, SGD. Command tanks T-55AD1M e AD2M.