I have an '06 wheel laced to a dirt star rim (tougher than Behr) with the '06 backing plate. The sprocket and rotor align correctly but the sprocket carrier backing plate does not go into the wheel by about 7~8 mm and that is the exact amount that the width of the complete unit with spacers is too wide.
Can you send me the part numbers for the wheel assembly, the backing plate assembly and tell me if the external spacers have a shoulder on them that are about 10mm thick? The internal spacer's shoulder in the wheel on the sprocket side should be about 1.5mm thick. So far as I can tell there is only one cush rubber insert ever made for the various combinations so that should not be where the extra width comes from. There may be a change from the '05 wheel assembly to the '06.