First question is really what size should I be ordering? Is the measurement taken from the very tip to tip, in which case 36-37mm?
Secondly, I'm aware that these lights only really need to point in one direction and there's no reflector behind them, so are there particular LED's that people would recommend (the new Audi ones only have the LED's pointing in one direction.... but I think that's on A3's and I think they're built into the unit). Any particular model that I should be ordering... I don't think mine has the bulb-warning system*, so less of an issue.
*I thought they all has the bulb warning system, but I've had sidelights fail a few times, plus tail lights, plus one factory fitted HID (gulp! ££)... not all at once, over the last four years, but never never a blip/flash from the DIS!