Hi,
I'm happy to provide an update here. I've bought recently a few more old bike magazines, I haven't had before.
In the Dec. 1995 issue of the German MountainBike Magazine I came across a nice article, helping to shed some more light on the mysterious TNT rear derailleur.
Unfortunately the origin of this nice bike part stays also with that a bit vague, but we do have now a prove point that it's an original bike part of the 90ties, created and sold in Austria.
English Translation by using Google
So, it's not from TNT, just TNT pulleys and some screws have been used, and it was produced by an unknown source in Vienna...
The brand was called G-Point, but before you guys start to google, think a second beforehand what kind of listings Google will bring up
The distributor was a bike shop in Krems, Austria, called Radstudio Krems.
This is actually still around, or let's better say partly still existing.
https://www.radstudio.at/Radstudio-KremsIt was founded in 1990 from Martin Kalteis and Lothar Herz. The latter one is still around and runs the bike shop at a different place in St. Pölten
https://www.radstudio.at/Radstudio-St-Poelten@MuchAlohaNui or
@Russell.Berrisford, if you're interested to get some more details, maybe reaching out to Lothar Herz may help to clarify this still a bit mystery production in Vienna, maybe also other details like how many have been produced.
Based on the article we do have at least a rough guess, that it was twice as expensive as a XTR rear derailleur and should work as well