Actually, I have customized my side markers in a much different way. I took out the oem marker lamp assembly's
Then hogged out the backsides to be able to accept red and amber bullet lights. Red/ rear Amber/ front.
They do not blink oposite the normal blinkers. More like running lights at dusk but still on while all other lights are turned on.
You can see them really well from behind the car too. Even the third brake light was converted to run these.
The outer was made from scrap aluminum and cut to an exact fit over the oem marker lamp housing and screw locations.
Then painted white to match the car. So the 2 screws and the body of the bullet lights hold everything together.
I split the harness hots and grounds and tied it all together. Works like charm. If you would like to see it send me and email...
jake miata_B_racing