Where is the starter selonoid located on a 1986 Chevy pickup?

On a 1986 Chevy pickup, the starter solenoid is typically mounted on the starter motor itself. It's not a separate component in most cases. You'll find the starter motor on the engine block, near the bell housing (where the transmission connects to the engine). The solenoid will be a part of that unit, usually a large cylindrical part with a couple of large terminals on top.