help me - routing factory speaker wires

[Flojo]

I'm further on detailing my 79 SC during rebuild.
While I'm in there I'm deleting all kinds of no longer needed wiring (antenna, AC, fogs, etc.).

I once kept the speaker wires tucked away for a later re-install but no.

On the co-drivers side the door wire goes up somewhere behind the glovebox through a grommet inside the frunk.
BUT, just before entering the grommet it goes Y and that split wire goes under the dash.
I believe the latter would go to the radio (if there was one) but it is not clear to me. I cannot pull it enough to reveal. strange.

so back to the other: where exactly does it go once passing the grommet into the frunk?
I searched a lot but can't detect it from inside the whole vent system is heavily blocking any view. dental mirror didn't help.

any first hand info?