So, as there appears to be some confusion about Dark Portal modelchange, i just gathered information 2gether and tried a bit on my own.
1. download this
( here I have to thank dRon 4 posting the link)
2. name the file you downloaded patch-enGB-8.mpq and copy it in folder /worldoowarcraft/data/enGB, if you use english version or
name it patch-deDE-8.mpq and copy it in folder /worldofwarcraft/data/deDE for german version
Here we go, it works perfectly !
Pic: