If you are after shortening the shaft on your Sim Jack Shifter try this out, it drops the height of the gear knob to bring the length down to more like the Heukensveld shifter.

100% non destructive to your kit and easily removable (you may need pliers to unscrew it its quite tight)

simply screw on as shown in the video (metal threads should not poke out of the top of the adaptor), and thread your gear knob on to the adaptor and you are good to go

stop tightening when it is on firmly, if you keep tightening it with great force you will destroy the adaptor, it does allow plenty of tightness for zero movement of the gear knob. 2 adaptors supplied in case you mess one up!

 

The sim jack shifter is avaiable for around £70 from Ali Express, it is all metal and carbon fibre and is very good quality for the price