The most reliable source for a clean, untouched 7.3.5 client is the from trusted emulation communities (e.g., AC Web, EmuCoach, or Model Changing net).
In this guide, we’ll cover:
If you actually need of the 7.3.5 client for personal archival/research (and you already own a license for Legion from when it was current), I can point you toward official sources like Blizzard's CDN downloader tools (e.g., CASCExplorer + Battle.net CDN URLs) — but those require technical steps and won't provide a simple "one-click download." Wow Legion 7.3 5 Client Download