The blue is for power antenna.
The brown is for ground... but you said you got two of them?
There is supposed to be two power... one is always constant power 12V and
one of them power on only when ignition is on. You will have to use
voltmeter/multimeter to figure this out.
Then you have speaker wires... each has ground and positive so in SL, you
probably got only two speakers... so that is 4 wires.
I believe the grey wire is for light... it gives you 12V When you turn on
your headlights. so you can see your radio at night.