Does the colour of the little on/off indicator light on the pre-amp give any indication about version, date or anything else, of the unit or is just matter of what colour was available at the time.

I think there are at least three versions. I had a very old one, and it had a different front panel graphic layout, sort of more like the original F2B in a way. The switches by the DI were arranged a bit differently and it also was not gain compensated for the deep switch (although there was a mod Ron provided for that). Mine also had no serial number, which was odd. I modded it with a post vol/EQ effects loop, too.
 
But I think they are all functionally similar.
 

Is that just your bass rack!!!

Oooh, I like that rocker switch on the *front* of the F-1X.
 
FWIW, mine is a new-ish model, and has a green power indicator.  
 
(Message edited by edwardofhuncote on April 04, 2016)

That was my bass rack in the late 90s. All the effects were replaced by a Lexicon MPX G2 around 2001 or so.