Mozilla Firefox Full Download for Offline Installation

Where Can I Download Old Versions of FireFox

Get the Most Current Versions
https://www.mozilla.org/en-US/firefox/all/

Download Past Versions
https://ftp.mozilla.org/pub/firefox/releases/

A Very Stable Enterprise ESR Version
https://ftp.mozilla.org/pub/firefox/releases/52.5.0esr/win64/en-US/

If you see this message:  "Gah. Your Tab Just Crashed" You may need to use the ESR version.