For some cars with mechanical secondaries that works but 6bbl setups with vacuum pods like to be shifted with your foot flat on the floor. A block under the clutch pedal to limit clutch plate departure, those rings, and a 10w-30 and atf mix in the box would get you right down the street. Gear oil seemed to make it a little harder to do it, straight atf was best, because it is thin and the rings grab the gear better/faster.