Dear group,
changing the shackle depends on the type of Antal 4150 car that is used. The more recent ones have two plastic retainer caps on top of the car. If you disassemble these caps (two screws each), you can slide out the bolt which holds the shackle.
Our horizontal bar in the shackle was broken, we cut it out and welded a new one in.
The anodized "dyneema link" looks like a simple and clever design. It is built into the same 4150 car as the shackle - if Antal/Amel sells it without the car it might be a good replacement. Otherwise a machine shop can built it without much efford. It is not advisable to built it in 316 and stronger, because it will not match the safe working load of the car and if the loads are getting too high it is better to brake/bend a cheap/simple part, not the car or the track.

Safe sailing,
Walter (Noa, SM2K 436)