On the 83 (and many others) the 8-amp No.1 fuse feeds the lighter, radio,tail gate wiper/washer and electric side mirrors. If it keeps blowing when you operate the radio you're going to have to solve that. The fuse supplied with the radio should be enough to handle it - what's it's rating? It should not blow with normal radio/CD operation- 8amps is about 100 watts of power, and regardless of what Sony says the deck will put out, it is unlikely to draw that much power.

I have an 81GL with the small clock and there is very little extra wire behind it - it could be a real chore to splice into the red (constant 12V) wire working through that small hole. I've installed stereo systems into both my 83DL and the 81, and prefer to tap into the fuse box -it's easy to run wiring from there to the radio area. Fuses 1,2,3 get power in the ACC or Ignition positions of the key. Fuses 6,7,8,9,10 are always hot. I'd go for fuse 8, which supplies a lot of low-draw stuff, none of which is safety related (like brake lights or hazard flashers). It has a green output wire. Before you start working in the fuse box, disconnect the battery's negative cable.