Innertube Stems

Since I got the Silca Professional floor pump from Andrew one thing has been a real pain in the butt. The threaded stems make it difficult to push the head on and pull it off.

I bought a whole load of inner tubes some time ago. While using them some of the inner tubes had the threadless stems. This makes it much easier to use ether with the floor pump of the CO2 fillers.

But looking through the innertubes for sale on eBay not one of them shows these threadless stems with a stem length over 51 mm to fit my Campy rims.

Does anyone know a source?