Where can I find the old KeeFox to re-install on Firefox 55?

I cannot use the new FireFox as it does not support my favourite add-on “LOAD FROM CACHE” - this add on forces Firefox to re-display rather than re-load every picture that has not changed. And turns my super slow internet into a workable beast.

Sadly Firefox autoupdated itself and updated the old KeeFox to the new Kee. Very nice, but no good if my internet is too slow to display the page!

I have re-installed FF 55, but how do I get the old KeeFox add-on back please?