possibly a deadly situation with a corroded battery terminal

Jerry;
The battery is there to start the engine. Once it is running the alternator supplies power. To have a full circuit you need a ground. Vehicles have a heavy ground strap from the motor to the frame. Sometimes there are other grounds as well. As long as the battery is connected the ground can go through the battery, but if the secondary circuit (engine ground strap) is disconnected, as might be the case in a 1998 truck, when the battery disconnects you also lose the only ground for the engine. No ground......no power>