I've spoken to the guy that makes them and he can cut the hole to any size and thread. I guess you can have anything you want inside the knob. For us I think we'd need to somehow fix it on top of the lift-up mechanism. Anyone got a picture of a gear lever without a knob?
Not sure about that. I guess it would need a thread cutting into the splined part.
the aftermarket knob I have has a small allen head bolt that screws through the front of the knob onto the splined part, should be easier than trying to thread the whole thing.