I would rather than going for Tatkal paying extra & not sure of getting CNF ticket for sure, book till ADI(Ahmedabad) for this train which falls under GNWL quota...
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The Fare difference for SL is just Rs.25/- & for 3AC is Rs.70/- which is way less than tatkal charge. Availability is there for later part of May, early part in WL but decent chances of clearing by DOJ if you book now.