Actually it depends from coach to coach that whether SMB is present or not. For example, some days ago, I had a reservation in Mumbai GR in which I had a SMB but after boarding the train I found that my coach don't have any SMB and my SMB seat number turned out to be a SL berth So.untill and unless u board the train u will not be able to understood whether the coach has 64 or 72 seats
Actually railway do so many types of experiments in there system.. few years ago this systematic arrangements have been taken to all trains SL coach but due to negative response this experiment are taken back.. but it's still in Garib rath. so u can be confident about ur seat position.. there is only 1% negative chance . Don't worry about that u can fix it in the train..
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