If you won't drill into the cage, that's going to be a tough one. It would totally depend on how your dash is constructed and whether there's anything to mount a bracket on in your dash.

I think you should consider drilling two holes into the cage and mounting a metal piece to it, then attaching the ethernet plug to the metal piece. Sort of like how Brian Mihulka did it on his component box, only you'll be anchoring the metal piece to the sled instead of the box.

Make sure to use bolts with low-clearance heads, going from the inside of the cage out.

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Tony Fabris