W126 - Ever remove the...
 

transmission shift knob? Does it thread on to the stick or does it lock down some other way?

It is threaded and secured by a locknut. You have to get at it from the side by pulling the indicator panel up (4 bolts)

There is a jam nut at the base. Get that loose and the shifter will spin right out. Thinking of a short shifter?

Nah, nothing that exotic... I was able to find a nice wooden knob to replace the original plastic/rubber deal. Problem is the replacement is from a later model without the stem so I'll probably cut the old knob off, reuse the stem and fabricate a slide on insert for the new one.