This is a custom content issue, FYI. You'll get more answers if you use that section of the NWN forum. No big deal. Just trying to point you the right way for best results. Next regarding your querry:
open your file c_granadora.mdl in textedit or notepad++ or whatever you use to edit pure text files.
You'll need to make two find and replace actions throughout the entire file
(1) look for the old texture name next to "bitmap", replace that texture name (every time it shows up) with the name of your new texture
(2) the old ettercap model name probably shows up a few time sin this model, find and replace all instances of it with the new filename - EXCEPT for anything to do with a supermodel. do not change any names after supermodel.
that should do it.