Is there any way you can get the knob off of the shaft?
Sometimes they are glued on and sometimes they screw on.
A buddy of mine bought a new shift knob for his 300E, and the knob was made to fit a W140.
So he cut off the old black knob with a utility knife, and glued on the new knob. Worked like a charm and looks perfect.
2001 E430, Bourdeaux Red, Oyster interior.
1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".