Hi @dlaws ,
The maintenance and service guide refers to 2 cables from the USB/Audio board.
One goes to the systemboard and the other goes to the fingerprint reader board.
Scroll to p.67 to view where the cables go to.
On p.24 it mentions the USB/Audio board connector cable as part of the cable kit (part # 721936-001).
Searching online using the part number only shows that you will get all the cables shown in the kit. It seems that you cannot get just the one cable when using the part number
When searching for HP Probook 450 G1 USB/Audio cable I only got results for the complete module i.e. board and cable.
You may have better luck sourcing just the individual cable.