a4ld governor, which do I need?

[CountryBoy704]

Looking at wittrans.com there are several governor bodies that they sell, anyone know how to identify which one I have? It refers to a small land on a valve being different sizes and to having 1, 2, or 3 grooves in the valve, what valve is being referenced here?

 

[CountryBoy704]

its an '84 single solenoid 4x4 model if it matters