How have you determined it's not working. Did you bolt on and torqure the yoke and drive it? or are you spinning the output shaft by hand? I'm assuming you haven't bolted up the yoke because you took out the driven gear. Is that correct? Anyhow, Put the gear back in and torque the yoke, if you haven't already. And drive it, you should have action to the speedo. There is no spacer that I know of.
j