GAA is correct. The A in this instance refers to it being the first (and only) variant. The BDA is a universal name applied to a whole family of engines. There was an 1100cc BDJ and a 1300cc BDH for example. The leters ran all the way down to the BDX which was - as far as I recall - an alloy version of the BDG. Robsons book states that the original Capri iron block was used, and that the heads etc. were aluminium. I read - back in the mists of time - that an all alloy engine existed somewhere..... In Ireland, GAA refers to a juggernaut!