Brake Hardware from Venus/Mars?

We have a '65 Valiant with what appears to be a junkyard '74 Dart 7 1/4" open differential that was transplanted by a previous owner. The springs retaining the rear brake shoes sure look strange to me, I have never seen anything like 'em.

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Rock auto "brake hold down spring" for 1966 Dart upload_2022-4-15_13-41-29.png