>>537393267
for IWP there is
https://www.moddb.com/mods/stalker-improved-weapon-pack/addons/fixed-vanilla-npc-models-for-improved-weapon-pack-fix (slightly fixed models and better textures)

or

https://www.moddb.com/mods/stalker-improved-weapon-pack/addons/all-vanilla-stalkers-variations-plus-lite (true stalker models, which were based on the addon that >>537395652
mentioned, iirc)