Yes 1GS & 1SLR is detached at Londa Jn. Actually 17305 is train no for Hubli - Londa Exp (1GS + 1SLR) terminating at Londa & its carries Hubli link of Goa Exp ( Hubli - Nizammudin Exp) along with it.
After Arrival of Goa Exp at Londa (Vasco - Nizammudin Exp), the Hubli slip gets attached to Main & leads the train.
I suppose very few/none may travel in GS end2end. But Yes known people will get into another SLR Coach to travel for longer distance. & unknown's will need to...
more... get in into GS coaches of Goa Exp.