The SVO should be the same as all 79 to 86's. It comes out from behind the dash. If its and oem style, it has knobs, and there are nuts on the tubes that the shafts come out of that hold it in, and probably a bracket at the rear. The dash opening is way smaller than the unit. May have a separate amp in there also.
Remove the console, etc, the knobs, and the trim plates over the ratio, etc.
It does take a while because there's so much stuff to unbolt.