Careful when you "old stock" has

+ A lot of fine, fast access, good overview, good protection, coupled fast for the particular application
- A lot of money, sometimes a waste of space

The newer T-Loc system has over the older with the 4 tabs per faster operation. Also vertical edges of Systainer were nearly 45 °. The coupling possibilities within the T-Loc series of the older models comparable.
The stability of the coupling has suffered a little while, but more serious is the lack of compatibility of the T-locs with the older models. T-Locs can indeed _über_ attach the conventional Systainers, but not _unterhalb_. This limits the optional coupling unfortunately a heavily.
Although the current juxtaposition of the two systems of buyers and suppliers requires more care, I hope that both systems remain. But I fear that it will not be so.

. Note If the image has not been updated, it is deceptive possibly - the Systainer is offered the relevant T-Loc model. Binding offer is the text, not the picture.