I must correct you that LHB trains can have 24 coaches ( check 12417/18) and yeah, the lhb trains who have 24 coaches can't run on 130 kmph. But here we have no speed relates issue. And aBout D1 to D4 maine khin dekha tha ki unreserved deen dayalu coaches k bahar D series se rename kiye gye the, that. Why maine rkh diya .. but confusion na ho isliye change kr dunga..