T-54/55 versions

[PlasmaKrab]

OK, thanks for the update, I thought at least part of the T-55As were modernized from stock T-55s.
Anyway, it boils down to the only difference between M and AM being, in game terms, the BMG.
I don't know if the old CMG has been retained while rebuilding the old T-55s to M standard, but when you're already taking out the stabilizer, gunner sight and probably gunbarrel, changing the CMG as well is no big feat.