Ok, I transplanted a 833 OD 4-speed into my '65 Valiant with a 3.21 gear and 225 70 14 tires. The speedo now reads much faster than car is actually going. I don't expect precision accuracy from a '65 Valiant speedo, but anybody have an idea which # of teeth on the gear wil get me close? I don't know if the OD is a factor, or just the change in rear gear.