This is the WIP for the Rear Axle with a diff inside.
You can finde here the jug for the Axle to build and the instructions in how to assemble still here:
https://www.instructables.com/HPD-F1-Carbon-Axle/
The main design for the axle was made by KentAsplund. Check out his HPD F1
https://www.thingiverse.com/thing:2218101
The author remixed this model.