Right front flasher works? If so that's the same large filament in the 1157 dual bulb as the RF turn signal & from the bulkhead forward you are OK. I'd seperate the dangling TS/brake pull apart electrical connector under the steering column with the TS stalk "up" I'd check continuity on the col half & need continuity on the hot wire "in" up to the TS switch and "out" on 2 wires (1) to RF and (1) to RR turn signal large filaments. If flashers dont work on RF holler back