The gear box is upside down in the pictures, the output shafts should be near the top. Flipping the box would put the short suspension mounts on the bottom and the longer mounts at the top, to complement the longer lower control arms and shorter upper control arms.
I believe its the gearbox he used for his 1963 Indy car. It has the same ribbing on the right hand side (when the gearbox is viewed right side up).
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