1971 mercury cougar radio

So im was dealing with a short that was effecting my brakelights and turn signals and i trased it back to the radio and its an old aftermarket radio but they ran the yellow to the yellow on the ignition and the red to one side of a fuse is the plug pictured the one im supposed to wire into?

single wire blue/red is radio lamp; two wire white/purple is fused power for radio.