Hi vdt,
my A3 is a 2006 but I replaced my original tail lights with facelift tail lights. Tail lights here in North America are configured a bit different way as they use red lenses for turn signals as well as brakes.
I bought my facelift tail lights from an aftermarket parts company in Germany - BKS Tuning (they no longer exist) and I believe they are same as the original euro facelift tail lights - with a clear lenses for amber/yellow coloured turn signal bulbs.
Here are my facelift tail lights:
View attachment 260279
These were light bulbs in there:
View attachment 260280View attachment 260281
View attachment 260282View attachment 260283
Note 1:
The turn signal bulbs have asymmetric pins (150 degrees) and are amber/yellow in colour. I believe this pin configuration is labeled as "BAU".
Brake bulbs are straight 180 degrees configuration that I believe is just labeled "BA". Both turn and brake bulbs originally come as 21 Watt.
There are 3 brake light bulbs on each side, 2 in the outer part (rear fender) and 1 in the inner (hatch) part of the tail lights, total 6 for your tails. Those inner brake lights are also used as rear fog lights, either left or both, depends how it's configured via VagCom.
I have replaced my turn signal and brake light bulbs with LED bulbs, bought them at AliExpress, not sure if these are exactly what I bought but I think these would work, you need to choose correct type (BA vs. BAU) and colour:
https://www.aliexpress.us/item/2255...tewayAdapt=glo2usa4itemAdapt&_randl_shipto=US
These bulbs give me no errors and don't need resistors. I am not sure how long they will last but for that price it doesn't matter much. Just buy some spares.
Note 2:
If you decide buying LED bulbs for your brake lights, make sure you choose red colour; white would look pink and not red.
Sorry I don't any info on back up (reverse) bulbs but they should be pretty straightforward.
Hope this helps,