Mumbai Local - RailFanning nirvana.

D1&D2 coaches have seating arrangement same as SL(3per Berth) , so you can enjoy SL in 2S fare.
You can't get proper lunch in this but snacks/fruits are available almost every time.
For 16853 in Ms VM section they will sell tea ,water bottle and some snacks, only few vendors will be there . At VM they will sell samosa,vada,cool drinks ,milk and lunch (sambar Rice/biriyani/curd Rice/chappathi&kuruma). Once the train crosses PRTY the train will be filled with unauthorized vendors who will sell Guava fruit, Jackfruit, Salted cashew, Groundnuts,Veg soup. you can...
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find at least 20 Guava fruit seller in this train , one authorized vendor will sell lunch and vada (he comes rarely).
For 16854 same applies till VM and from VM they will sea tea &snacks . If you start the travel from your home it is advisable carry Lunch.
Punctuality Tip: will get delayed at all intermediate station but will reach the final station on time or with neglible delay(most of the days)