I´ll answer in english.

The mechanic should be able to find that seal, if he can't he should call Estanfi, wich is the spanish distributor of Britpart spares.

Otherwise Anglorecambios.com should have them, probably in stock, and can send it to you for the next morning, you can call them (916433655) they are very polite:
http://www.land-rover-parts-shop.com/es/ui/search.php?q=AEU2515&stp=s

You could also go to the local Land Rover dealer.

You can also Air-Mail order them from lrseries, if you call them, they'll say you if they have'em.
http://www.lrseries.com/shop/product/listing/2372/AEU2515-OIL-SEAL-RUBBER-REAR-DIFFERENTIAL.html?search=salisbury%20seal&page=1

Ultimately, the seal specifications are these, so you could find them in a bearing shop.
National 9316

http://www.oreillyauto.com/site/c/detail/BCA0/9316.oap?year=1966&make=Chevrolet&model=C20%2BPickup&vi=1321917&ck=Search_01454_1321917_-1&pt=01454&ppt=C0362

Have a nice trip!!!!

Garmen: Detallazos como èste tuyo.....¡Hacen este Club MUY GRANDE!

(Y a mi se me ponen las venas Epsom Green  😉 ;))

Gracias

Good Luck Michal !!!!

Me estaba imaginado yo con mi Series en un pueblo de Chequia, con el retén trasero del grupo chorreando.

Aunque yo seguramente llevaría repuesto, o un diferencial entero. O directamente llamaría a LrSeries.

Pero seea como fuere, he entrado y me ha extrañado que en 7 horas nadie le haya respondido.

Hi guys,
thanks for all your responses. They get new genuine seal next day and replaced it. Unfortunately, after a while it started leaking again:( So I did another 6000km with refilling the oil and wait to repair it in Czech rep. After that I found LR parts dealer near Barcelona with aftermaket parts...

Thx again
Michal