Jim, for your c140 car its different than for W124 models.
The shift knob is attached to the shaft, and is one piece on pre 1994 mercedes w124 cars I believe.
This is how I did it on my 1992 300CE:
Lift up center console carpet.
You will see a screw on a little tab off the center wood console. remove it.
Pry out shift plate surround piece carefully as to not damage the wood or break anything.
Once it is out, lift the console wood off by lifting up from the area you lifted the carpet from. Lift gently and carefully as to not crack the wood.
Once it is off, you can pop the shift plate loose. there should be some plastic clips holding it on that snap into place and are attached to the shift plate.
Once it is loose, get an open ended wrench that fits the bottom of the shaft lock nut at the bottom of the shaft. I forgot the size, but it was not a big one, but not tiny. I think somewhere between 8mm-12mm max.
Once the nut is loose, unscrew the knob and replace with the new knob, get it lined up right, tighten the lock nut, and reassemble.
Shouldn't take too long in the W124.
I did it when I got my burlwood shift knob in less than an hour.
'92 300CE - Sold
2004 C240 - C7 Wheels
2015 ML350 - P1, Pano, Ash poplar wood, Sport Dinamica interior, Running Boards Keyless go.