x-notifier 3.x download page

Dear frends, could you please provide the link where the last (with all possible changes) x-notifier 3.x for firefox version can be downloaded as a separate file, so that it can be added manually. Also, please advise what it the last firefox version where it can be used?

Firefox 56.0b9 is probably the last regular release that runs X-Notifier 3.5.23
(Firefox 57.x blocks installation of X-Notifier 3.x.x.)
(You can also try the Firefox Extended Service Release52.9.0esr, perhaps.)
You can find both of those at:  https://ftp.mozilla.org/pub/firefox/releases
- To get the old versions of Firefox for Windows...
Go to the link above and click the folder named for the FF release number you want, find/click the win32 or win64 directory (depending on your computer processor version),
then find/click the en-US directory (for US English)... 
and download the "Firefox Setup" .exe  installation file.

(You'll see other operating systems and languages directories also.)

X-Notifier 3.5.23 is the last version released by the developer of the addon...
...it can still be used if you manually find the updated scripts (Hotmail, Gmail, etc) ...which are often linked in the user posts/comments in the X-Notifier forums (or for other custom scripts, perhaps on the Scripts pages)... and then download and add them, just like custom scripts, to this version 3.5.23 of X-Notifier...

X-Notifier Reloaded (now version 3.5.26) is a 'fork' (modification) of the original X-Notifier 3.5.23 that is maintained by others (not the developer) to include updated scripts (for Hotmail, Gmail, etc)...
...as the scripts are still updated for newer versions of X-Notifier (and then someone 'extracts' them from the newer versions of X-Notifier, and then they are either included in the next version of X-Notifier Reloaded, or... someone posts the updated script to the forum, where you can download and add them (again just like any other custom script) to your current X-Notifier Reloaded version.

X-Notifier for Chrome (Opera, Safari) still allows for customs scripts and is still maintained by the developer (including updates for Hotmail, Gmail, etc). 

RpD, thank you!