If you're looking into a dog shifting setup, the WCP PTO add on kit includes the shifting hardware to shift into a gear, or a sprocket/belt. It was designed for mechanisms requiring shifting/releasing, it interfaces into the PTO, or you can put it into a custom gearbox. The WCP DOG is made of stronger 4140 Steel, and is thicker for more strength, and allows the use of a roll pin to prevent shearing the dog screw.
Links
WCP DOG 217-3636
Hopefully this helps