Yes, you are correct, they are current ÖsterreichischesBundesheer issue for their MG-74. So far as I have ever seen, they all seem to be made by Glock as you note. I asked Gaston's son at the Glock party in Vegas a couple years back about their participation in this, and he indicated "they made them all" with a smile. Not sure if I believe that......
They are a REALLY nice link arrangement, MUCH easier to load by hand singly, they seem to give more consistent stripping pressure than either the Gurt-34 or DM-1 belt loops, and they are of course dismountable so you can shorten or lengthen belt length at will.
For shooters of live MG's here, there is one problem though in that you can't easily run them through a MG3 belt loader machine as they won't fit the star-wheel precisely. See pictures below:
Picture 1, DM-1 belt fitting the star wheel precisely:
Next two pictures showing poor fit of MG-74 links in star wheel:
....this is due to the pitch of the links being a bit different than the more common Gurt-34 or DM-1 belts, see below:
...MG-74 belt pitch is visibly more narrow than DM-1 pitch, so the MG-74 belts won't lay in the MG3 belt loader star wheel sprocket correctly. You can do it, but you have to be watching to keep the next-in-line MG-74 link from catching on the sprocket tooth as you feed.....a pain, but do-able.
I have not tried it with either an Gurtfuller-34 or 41 machine yet......though there may be some more available tolerance in the GF34, enough to use it with MG-74 belts successfully. I doubt much success will come trying it in a GF41 as, again, the pitch will interfere.
I think it really worth it as the MG-74 belts are just really so nice to use. Of note, I have noticed no discernible distinction in actually running my Steyr MG-74 with "correct" MG-74 belts, MG3 DM-1 belts, or Gurt-34 belts. It doesn't seem to matter, the differing pitch. I also can't measure reliably any distinct difference in the actual feed cam angles between the MG-74 and my MG3. Lacking any official information as to why they chose to alter the pitch, I am left to make some assumptions relative to the need to facilitate the links being easily disassembled.
-TomH