It is not stock. I have seen this shift knob on a few Panteras. It had a flip up top with a switch to enable nitrous because you never know when you'll need an extra 100hp at wide open throttle.
I replaced it with stock as you can see in the photo below. The flip up top has been JB welded shut. But no damage. It is nice. I could not get the shift rod to dislodge from the knob base and did not pursue it because there would probably be marks on the rod that would show with a stock knob. Hence it comes with a shift rod.