They did exist in black, back in 1978 I had a Black K3.
On returning to the K3 ownership I found myself with the Brown version, but I kept hankering back for a black one ('my first love', as they say...)
- I couldn't find a code for Excel Black either, but I came across a guy near Cirencester who did me a fine spray job, including some excellent hand painted pinstripes instead of tank decals.
Andy C