AA M80: f-y;
AA M83: --y;

M83 is f-y, same as the M80. These are both Mad Dogs (McDonnell Douglas Super 80 variations) and the workhorse of the AA fleet (though being phased out as fast as AA can afford it, to be replaced by 737-800s). M83 is (I think) the ones they got from TWA. The aircraft may be 'technically' different (different engines etc.?) and the 'old' TWA planes had different interiors when they were first acquired but I think they have all been retrofitted at this point.