The UpgradeMod_v1.zip file you have requested: Modifications / Upgrade Mod / Upgrade Mod v1 - 1.57kb is not available. Perhaps try browsing all files for the game S.T.A.L.K.E.R.: Clear Sky and upload any files you want to share or are missing. This is the only information we could locate:
Upgrade Mod for STALKER - CS. It allows the upgrading of any weapon or armour at any mechanic.