wire color behind stock radio, installing Options

[Cormudgen]

hello,

i'm looking to find out if anyone knows what color the wires are in a stock harness for a rear speaker. i'm putting in a line level converter right behind the radio b/c i already have rca's run from there and need to keep them there for when i put in anohter aftermarket deck. from lookin at where an aftermarket harness plugs into the toyota one, the right rear ones seem to be a red and white wire but that just doesnt make to much sense to me and i want to verify before i start splicing into stuff.

thanks
cormudgen