In the PC version of III all textures in generic.txd were downsampled to 64x64. I tried to find higher resolution versions of the textures, many of which are still in III in other txds, others were taken from the PS2 game or other GTAs.
generic_iii_diff.txd contains the changed textures only. You can load it with TEXDICTION from default.dat or gta3.dat after generic.txd
generic_iii_pc.txd is a complete replacement for PC generic.txd
In VC it looks like the file was downsampled for all versions, but not to 64x64 uniformly. Again I tried to find the best higher res textures in other txds or other games.
generic_vc_diff.txd contains the changed textures only. You can load it with TEXDICTION from default.dat or gta_vc.dat after generic.txd
generic_vc_pc.txd is a complete replacement for PC generic.txd
generic_vc_xbox.txd is a complete replacement for generic.txd when you're using the Xbox map