... snip ...
> I'm not sure how you want to retrieve it, but using Firefox->Tools->Web
> Developer
How did you figure that out?
I used that Firefox->Tools->Web Developer tool
and looked at everything that was fetched.
Besides the main HTML, a bunch of JS files and image files,
the only other file it fetched was the one I mentioned, so I looked at its
output to find it was a JSON file, and one of the first fields
was your version number.
Problem solved (60 seconds).