Thats what i am telling here.Loco link is not a passenger amenity subject yes it dose matter for rail fans.
Loco link is a pure technical matter and only DME or subordinates know which loco they will use today or with which train.
I have seen Bangarapet-Bangalore Exp with WAP7 but it dose not proves that WAP7 is permanent loco link for this train or train will run very fast with this loco.