I just bought a Delrin Hardbar from LAPD, one of the supporting vendors on a B&M Ripper Shifter.
Link is: http://www.stores.yahoo.com/corvetteforum/harblacdelsh.html
The Delrin Hardbar has a nice feel and is threaded to fit right on the stock threads. My only complaint is that it is a little narrow. I would've liked it to have a little more heft.
I used to have one of these: http://www.partsforyourcar.com/corvette/
Although I liked the look and feel of this shifter, despite what it says in the add, it does not thread directly on the stock shaft. It comes with plastic inserts which you are supposed to be able to "self thread" by screwing them on the shaft. This doesn't work. I went through the trouble of tapping and threading one of the inserts, but I still could not get this shifter knob tight.
I will sell one for cheap...
I think that only West Coast Corvettes carries those knobs.
I have to ask, off this topic -- Is that yellow console an overlay, or is it the stock one just painted yellow? Man, it looks great! There's something about the standard gray radio and AC controls being surrounded by something other than black that just looks so cool to me!