Lot 742 or 744 seem almost certain to be Falcons however the only sure way to tell (without peering inside the Xbox with a torch) is the presence of a 175W power brick, unfortunately most of the packaging still shows 203W even if a 175W brick is enclosed! Some Falcons do come with the 203W brick so all is not lost if you get one of those, you just need to peer inside and look for 2 coils not 3 as per the Anandtech article
here.