Where does someone go for extra special pot?

I'm thinking of how to add manual blower control, or more precisely blower speed adjustability to my 87 300D similar to the blower control in an early W140. The early W140 has a thumbwheel with detents at min, auto and max, corresponding to the min, auto and max blower settings in the W124 ACC. What's cool in the W140 is you can turn the thumbwheel so you get a little more or less air than the auto setting. In the W124 it's gale force, auto or butterfly f@rt.

To accomplish this, I need a special kind of potentiometer which I imagine looks/works something like this -



I see nothing of the sort in the Digikey catalog and I can't do the custom work required to two basic pots to roll my own. I was thinking an audio fader comes close; but again requires some custom work. Would be nice to put that idle fader thumbwheel to use. There are C4C W140s at the PnP but all the PBUs are gone.

Does anyone know of an off-the-shelf pot like I described?

One concern is the ACC might continuously challenge the adjusted blower setting putting me in a never ending battle for comfort. I hope it's tolerant of small adjustments.

Thanks,
Sixto
87 300D