LTT doesn't have restriction like DR for 18 Coaches only,if not 24 coaches easily 2-3 coaches can be added..So better keep Gen as it is for the time being and add 2 SL & 1 3AC or 1 AB...Later if they think 6 Gen s of not that much use can trim 2 of them and add 1 SL & 1 AC Class.