The following Hogue Cowboy Action grips will fit Ruger New Blackhawk, Super Blackhawk Short Barrel (4.6" & 5.5"), Old Army, Vaquero and New Single Six models. These models are sometimes referred to as having XR3-RED grip frames.
Cowboy Action grips will fit models with or without the internal locking mechanism.
How to fit to a Bird's Head style grip frame: Simple place each grip half in turn and trace the frame outline on the back of the grip. Then cut and sand to shape.