No power at all...no horn, lights, radio, etc. Turned the key and heard 1 small click then everything went dead. No power on "Accesssory" or "Run" positions. New battery. Was working fine 5 minutes before. Truck started w/out problem like it has since it was new. I'm thinking one of the rectangular metal 20amp fuzes or one of the fusable links on the firewall. 1/2 ton, 4.3, 5 speed, 318K miles. All original, no modifications; has been a trustworthy and loyal partner for 21 years.