definitely not a GDM-1950/1952 or anything close. In fact HP had a
newer monitor that was bigger and more grotesque then this one (that one
had a plastic cover w/no swivel base, this one is metal).
Haev you looked on the Australian HP Museum site
(
http://www.hpmuseum.net/)? You might find a luser manual there, which
might give you the horizontal and vertical freqeuncies. There might even
be a CE manual (aka boardswapper guide) which occasionally contain useful
infromation.
-tony