firstly, get the IMG TOOL here
{With this tool, you can modify things in the :Player,weapons,cars,etc.}
Then, extract the .txd file which you want TO BE REPLACED [using IMG tool] as a BACKUP.
Then, delete it ONLY FROM IMG TOOL.
THEN, add the downloaded file in the sameplace using Add file option.
Then, select option Rebuild Archive.
Wait till it completes.
Then play !!
Hope this helps