This simple bushing adapter is designed to snugly press fit onto the Thrustmaster TH8S sim racing gear shift lever/shaft in order to easily accommodate your preferred shift knob. It can accept both threaded knobs and set screw knobs.

I have uploaded the raw files so that you can adjust the outer diameter of the model in your preferred CAD software to fit your specific shift knob. You will want a good tight outer diameter fit for threaded knobs, so that the threads get a good solid bite onto the printed part as the knob is screwed on.

Just for reference, the knob that the uploaded model/files were made for was a vintage 1960's Ford Mustang shift knob.

It's a small, simple, fast print that uses very little filament, so you can afford to print several prototypes until you get the one that fits just right for your application.