A metering device for dispensing granular agricultural product from a bin, wherein said metering device comprises: a housing (40, 42) enclosing an interior space; and a metering assembly removably received within the interior space of said housing, wherein said metering assembly is configured to convey agricultural product through said metering device, and wherein said metering assembly comprises - a rotatable sub-shaft comprising an elongated, hollow cylinder with an interior passageway conformable to an exterior surface of an associated primary driveshaft, a first metering wheel positioned on said sub-shaft and configured to rotate with said sub-shaft, a second metering wheel positioned on said sub-shaft and configured to rotate with said sub-shaft, and a dividing element positioned on said sub-shaft between said first metering wheel and said second metering wheel; wherein said sub-shaft includes an elongated keyway formed along its exterior surface, wherein each of said first metering wheel and said second metering wheel is formed with a key on its interior surface, and wherein engagement between the keys of said first and second metering wheels and the keyway of said sub-shaft provides for the first and second metering wheels to rotate with said sub-shaft. a housing (40, 42) enclosing an interior space; and a metering assembly removably received within the interior space of said housing, wherein said metering assembly is configured to convey agricultural product through said metering device, and wherein said metering assembly comprises - a rotatable sub-shaft comprising an elongated, hollow cylinder with an interior passageway conformable to an exterior surface of an associated primary driveshaft, a first metering wheel positioned on said sub-shaft and configured to rotate with said sub-shaft, a second metering wheel positioned on said sub-shaft and configured to rotate with said sub-shaft, and a dividing element positioned on said sub-shaft between said first metering wheel and said second metering wheel; wherein said sub-shaft includes an elongated keyway formed along its exterior surface, wherein each of said first metering wheel and said second metering wheel is formed with a key on its interior surface, and wherein engagement between the keys of said first and second metering wheels and the keyway of said sub-shaft provides for the first and second metering wheels to rotate with said sub-shaft. a rotatable sub-shaft comprising an elongated, hollow cylinder with an interior passageway conformable to an exterior surface of an associated primary driveshaft, a first metering wheel positioned on said sub-shaft and configured to rotate with said sub-shaft, a second metering wheel positioned on said sub-shaft and configured to rotate with said sub-shaft, and a dividing element positioned on said sub-shaft between said first metering wheel and said second metering wheel; wherein said sub-shaft includes an elongated keyway formed along its exterior surface, wherein each of said first metering wheel and said second metering wheel is formed with a key on its interior surface, and wherein engagement between the keys of said first and second metering wheels and the keyway of said sub-shaft provides for the first and second metering wheels to rotate with said sub-shaft.