If you find a standalone "GTA IV 1.0.4.0 download" on a torrent site, you are walking into a minefield. Most are packed with malware, keyloggers, or broken DLLs. The safe path is using a downgrader script on your legally purchased copy.
Before you hit that download button, you need to understand what makes this patch so special. Rockstar’s patching history for GTA IV is a tragedy in three acts. The original release (1.0.0.0) was a buggy mess. Patches 1.0.2.0 and 1.0.3.0 improved stability but broke mods. Then came 1.0.4.0. Download Gta 4 1.0.4.0