The catalog I have only shows the knobs.
If you give them a call on the 800 number or ask via their website, I'm sure they have one for the 123's.
I hope he doesn't mind my saying, but my buddy who cut off his black knob and glued on the new one is Hi-Power. PM him to ask how he did it.
2001 E430, Bourdeaux Red, Oyster interior.
1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".