Isn't the turn/stop lamp physically the same bulb ? If so and the bulb works well in the turn function, then the bulb itself and grounding aspects are fine. I think the problem likely resides in your turn signal switch which also controls the stop function
Vivek
- 'Big Blue 2WD' - 1984 F350 RWD 460/C6
- 1978 Bronco with the heart of a 1986 F250 Bullnose - under restoration
- "Bonded Bronco" -1985 Bronco - 302 4-speed fuel injected, Hibernating future project