Tanks and APCs with Turrets in the game do not have differentiated Armour Values.
Both 1e and 2e1 (and TW2013, dunno about 2e2 as I never had a copy, though I expect it did as well) ALL had separate Armour Values for Turret and Hull ... for the simple and obvious reason that the real world armour values ARE different for these components.
This is a *serious* shortcoming IMO. It really needs to be changed/corrected even if only as a 'grognard' option.
Author: Space Opera (FGU); Rigger Black Book #1 (FASA); Orbis Mundi 2, The Marketplace, Ithura & Porthaven, Fantasy Europe (PGD); Road to Armageddon & Supplements, Displaced, Audace ad Gloriam, Farm, Forge & Steam (PGD).