OBJ.CRF/MESH.CRF

These are the original files. There are two selections required. The first one is the large .crf file usually stored in your RES folder (e.g. C:\games\Thief2\RES\OBJ.CRF). This contains the majority of files.

The second selection is the .crf file in your root Thief folder (e.g. C:\games\Thief2\obj.crf). The files in this will override files of the same name in the other .crf. When Thief 2 was patched to version 1.18, updated files went in these smaller .crfs

A normal Thief 2 installation has two sets of .crf files. Select I don't have this one if you installed the game with Tafferpatcher, which combines the .crf files, or if you combined them yourself.