by Russ » Wed May 19, 2010 2:52 am
If all you want to do is use the turn signal light as a tail/stop light you don't need to change the bulb socket.
Use an single filament 21w bulb or an LED is you can find one that fits. Connect the wire to your tail light power supply but with a resistor in line. This will cause the the bulb or LED to glow dim. Run a power wire into your brake light switch and after the switch run the power directly to your buld or LED. When you hit the brakes the brake light switch 'shorts out' the resistor and the bulb or LED glows at full strength.
You may have to play around with different resistors to get the right balance, I think 3 or 4 ohms is about right if your using a bulb.
I can post a wiring diagram if the above doesn't read too well.
Be Lucky