- Yes!
- No!
From October 1967 to 1970 the NVA received a total of 333 T-55A and T-55A(P) MBTs to strengthen their now rather weak fleet of T-54-51 and T-54A tanks. The T-55As were delivered by Czechoslovakia, while the T-55A(P)s were delivered by Poland. The destinction between the two was, firstly of course, the (P) designation, standing for Poland and the Polish T-55A also had a hydraulical steering-aid mechanism, which however would probably not impact the tanks performance in War Thunder, since the steering-aid just reduced the restistance of the steering-rods for the driver and reduced the working-range of the steering-rods from 400mm to 160-190mm.
The steering-rods were also in front of the driver, between the legs, instead of being on the sides of the hip. The only difference in War Thunder would be the designation.
This would be the decision of Gaijin and would also depend on which version they would choose, so from here on out, I will refer to both the T-55A and T-55A(P) as T-55A.
However, the NVA T-55As were not issued with any sub-caliber ammunition until 1971, when east-Germany started receiving BM-8 and BM-20 APFSDS along with the modernized T-55AM obr.1970.
This means we could get the T-55A with a pre-1971 ammo-selection, with access to only APCBC, HEAT-FS and HE (BR-412D, BK12M and OF-412 respectively).
Of course the decision would lie with the developers and a T-55A with APFSDS (BM-8 and BM-20) would of course also be a welcome addition.
An additional way the German T-55A could differ from the Soviet one, besides the NVA-markings, could be the two storage-boxes which were mounted on the left turret-side of most east-German tanks. These boxes were also used extensively by Polish T-55’s.
Side-vew:
(with beautiful winter-camo)
More pictures (some with the two extra storage-boxes on the left turret-side):
Specifications:
Crew: 4
Combat-weight: 36T
Power to weight ratio: 16,1
Lenght (with barrel): 9m
Lenght (hull): 6,2m
Engine: “W-55” four-stroke diesel V-12 (580HP)
Armament: 1x 100mm “D-10T2S” cannon with 43 rounds / 1x 7,62mm PKT coaxial-Mg with 2500 rounds / 1x 12,7mm DSchK AA-Mg with 500 rounds
In my opinion, this MBT would be an excellent addition to the German tech-tree. Either at 8.7 with APFSDS (post-1971 ammo-selection), or at 8.3 / 8.0 without APFSDS (pre-1971 ammo-selection). Either way, I would love to see it being added, with or without Warsaw-Pact match-maker.
Thank you for reading!
If you spot any mistakes, or want to add something to the suggestion, just let me know!
Cheers. 
Sources:
