Before taking the plunge, I decided to take the old knob off and check the fixings / dimensions. As you can see from the pic below. Fitting the Renegade knob would have meant filing a flat on to the gear stick. So I decided against that, and went down the refurb route. Clean and flat with 1200 grit, 2 coats of aluminium paint 4 of clear lacquer later. Job done. Total cost; zero as I'd the paint left over from another job. I still might look for an alternative, but I don't dislike the original. I'll see how this turns out.