HP 5360A computing counter info sought

[Nolan Lee]

Last weekend, I was given a boatanchor counter package of the
first magnitude that I'd like to find some info on. It's been
running for about five days now and seems solid and on frequency
within a few a few tenths of a cycle at 100 MHz so I guess that
the current NASA calibration sticker is valid after all. :-)
I'm curious as to the time base used. It appears stable as hell
even by todays standards. The vacuum cleaner sounding cooling
fan is a major plus, too! :-)

It's an  HP 5360A "Computing Counter" with a serial number of
1136A00768. It's the only 12 digit nixie counter that I've ever
ran into. It looks to be of later 1960's or early 1970's vintage.
I'm guessing that this was a pretty serious counter for it's day.

I'd like to find a manual for it and the plug-ins. The mainframe
contains an HP 5365A Input Module with serial number of 1136A00775
and a 5379A Time Interval Plug-In with a serial number of 1136A00651.

I'd be interested in hearing any information of insight that you
might have on this beast.

thanks in advance,
nolan