On this parts fiche the Bolt(10x33) is the most specified component.
The most reasonably priced component used on the Vl1500 Intruder 2003 (k3) Usa (e03) Front Caliper (model K2/k3/k4) is the Cap(od:12).
Check out any of the nineteen Front Caliper (model K2/k3/k4) components enlisted.