While trying to install a mod that added entries to placeables.2da, I came across a relatively severe limitation in KotOR that I feel should probably be known to anyone attempting to make or use large-scale or placeable mods. Maybe this is known or was documented on lucasforums, but I didn't find it anywhere.
Unique placeables defined in placeables.2da are limited to 256 (0-255). If you use a value higher than 255 for 'Appearance' in a UTP file, it rolls over. So 256 = 0, 257 = 1, etc.