Where is the turn signal flasher located on 1978 Toyota pickup?

There is one flasher that works both the hazard lights and blinkers. It is a 5x5ish silver box mounted to the firewall behind the radio. It has a two- prong connector on the face. If your hazard lights work and the blinkers don't or vice-versa, your problem is not the flasher. The hazard light switch does all of the routing of electricity to the lights based on its position and that of the blinker lever. The switch is purely mechanical and often gets oxidation on the contacts. Remove the switch, open it (careful for the springs and floating contacts inside), clean the contacts with emery cloth, reassemble, and reinstall. With luck, this will take care of your problem. If the flasher itself is your problem, you may have to go to Toyota for it. The ones that AutoZone and other parts stores sell are three prong, so they won't work.