I'm a bit confused on what aircraft AA operates of DFW-LHR and LHR-DFW. The information on AA.com sometimes varies with what is displayed on flightaware.
AA50 / AA51- Clearly a 77W.
AA78 / AA79- 77W (on aa.com) or 772 (on flightaware)?
AA80 / AA81- Seems to switch back and forth between a 763 and 772. When do the switches occur?