Hello,
here are some data concerning the German links for aircraft guns :
The MG17 is fed with a non-desintegrating belt both 250- and 500-round.
Connection between individual links is done by a pin. This belt has almost not fanwise flexibility.
Here is the early Gurt 17, later designated Gurt 17 a.A. (alte Art = old model):

Here is the late Gurt 17 n.A. (neue Art = new model) :

For the feeding of the MG81, a belt with enhanced fanwise flexibiliy was required. The corresponding belt is designated Gurt 17/81.
At least 6 different models have been identified.
Here are 5 different models :

The first model on top is non-desintegrating with the split-hook engaging the divided eye. All 4 other models are desintegrating.
The last model at bottom with solid hook is the standard model from 1943 on.
Indeed the French desintegrating links for the AA52 were derived from the last model of Gurt 17/81.
Here is a comparison of the last model of Gurt 17/81 on top and the earliest French link for AA52 at bottom. The main difference is the shape of the part which engages into the cartridge groove : for the German link it is a stamped circle, for the French link is recurved V-shaped.

For those interested in that subject, you might check my articles published in the US magazine "Small Arms Review" :
- Vol. 8 n°2 , November 2004 : "Belts for MG17 and MG 81 aircraft machineguns"
- Vol. 11 n°10 , July 2008 : "Belts for French AA52 machineguns"
Cheers
JFL