I don't know if the 1920 had the same parts as later models. My 1922, with Stewart-Warner speedometer, has a drive chain, not a cable. The chain broke a couple of years ago, as you can see on the picture, at the end at the U-joint.
The flat part of the end, to which the chain is fixed, slides into the tube part when you mount the drive chain assembly to the U-joint.
The chain collapsed because the magneto aggregate axle stuck. I had the speedometer fixed, and a retired fine mechanic made a couple of new links.
Maybe it is easier for you to find new production cables that fits.