Here we go...Electrical problems

[vstech]

OK, I have a 1982 300 SD, and I Stupidly left it parked OUTSIDE for 4 years in Humid Gaston County NC... I know sorry. (man will that mildew smell EVER go away?)
well now I am determined to make this my daily driver so I gotta fix all the electrical problems.
the hazzard/electronic radio fuse when connected will drain the battery. and the radio shows odd display. I plan to remove all the electronics from the dash and replace. I have a donor car, but MAN this looks daunting. (everything worked fine when I parked the car... STUPID STUPID STUPID!!!)
A/C will not energize, tach no go, although it does swing all the way to 6000 when the turn signals are on???
and the turn signals don't blink, well they do, but it is so fast it sounds like a buzzer and they look solid.
also, the cruise control worked when I started driving it again,but now it is also gone south... cleaning may help, but I bet it has condensation corrosion too.
condensation for 4 years will really wreak havok with theese cars.
anybody got any suggestions on where to start?
John