Does it look like this ? I got this one in a bunch of parts from a good friend that owned one of the most original and low mileage '68 SS 350 cars I have ever had the privilege of witnessing. He sold me a bunch of small parts, odds and ends, after he sold the car off during divorce proceedings. I've wondered if this stick is correct for an SS or a Z, obviously my '68 Z could use it if it is indeed correct. Marked with an "M", says "Use SE Oils", no stamped part number. Tag number does not match the 239 you list, but it appears to be the right length, gray tip (or where the tips a lighter gray?), round handle.
Regards,
Steve