The Galco Combat Master in the link above would be one of my first choices for an OWB holster for the 3" 856. Galco also offers the "Paddle Lite" holster on their site. The Silver Dollar holster from Simply Rugged would be another one to look into.
Most all of the kydex ones I've seen (Phlster and Harry's) have been IWB/AIWB ones.