ECU lower chamber seal

Hi, the driver's footwell is flooded & I'd already removed the rubber seal under the battery. I've found the source of the new leak & it's bad. The rubber seal between the bodywork & the ECU lower chamber has split & is hanging down into the electrics below the dash. Considering the amount of water I can hardly believe that the electrics are still going. Anyway, I'm looking for a replacement seal & can't find the part number in ETKA or online.

Does anyone know the part number for the seal?

Thanks,
Paul
A4 B6 Avant Quattro AVF 2004

Thanks for the advice, QC. Actually, I was pushed for time (other B6 got SORN'd a week after my original post) so had to buy the lower housing since Audi don't sell the seal on its own - of course they don't! I'll keep the Sikaflex in mind for future, though. Cheers.