check the mechanical ignition switch that is bolted to the column.
there should be a brown wire on its own butt connector, if i remember correctly that is the power for your wipers, heater motor and audio.
look for corrosion, warpage due to high heat and resistance. you have a chevy column so its going to be roughly ten bucks at most auto part stores.
pain in the ass you get to though. remove the lower most dash piece with the cig' compartment and where the 2 stock tweeters go. then 4 bolts, two bolts on the firewall at the base of the column (might need to pull back carpet) and two more farther up the column where it meets the dash.
the column then can drop into you seat and you will see the ignition switch and the 3 connectors going to it.
