Okay here is the completed Proxy model for the basic ankle joint.

It is fully rigged. The top (entire ankle) rolls around the x-axis, the middle section with the pistons rolls around the z-axis (about +- 45 deg), and the bottom section rolls 360 deg around the y-axis.

I plan on completing the entire high res ankle assembly at a minimum. But I hope to complete the entire proxy and high res and completely rigged model in Maya.

Cheers