Looking for a service manual, 79 GMC Sierra Grande, or a 79 Silverado manual, any pdf files flaoting around here someone would share with me?

Currently trouble shootin some electrical issues, starting with the main headlamps, they died out on me and I swapped the floor dimmer switch since that seemed to be the culprit, still a no go. Can not seem to find any sort of fuse either for the headlamps, in the box or in-line. Checked the on off switch on the dash, no issue there either. Any suggestions?