my turn light is my arm

Time to dig into the service manual. The 73 and later manuals WERE A BIG change because the diagrams are drawn completely differently but they are much better documented as to actual wire paths and interconnects and splices.

Start on page 8-162 and find the fuse at top left Wire C1-14BK goes off and feeds the HEATER BLOWER and branches off from there with wire X12-14R