The Train's Coach composition is inverted in the alternate days.
I traveled on this train which departed from CSTM on 11th of June and the CC was
LOCO-SLR-S1-S2-S3-S4-S5-S6-S7-S8-B1-B2-AB1-A1-GEN-SLR
Meanwhile while spotting 12133 at 10th June in CSTM, the CC was
LOCO-SLR-GEN-A1-AB1-B2-B1-S8-S7-S6-S5-S4-S3-S2-S1-SLR...
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The SLR coach that is attached with the sleeper part is opened only at Thane.