The speedo gears will not swap. The internal gear on the output shaft is a different size. Most likely, the car the trans came from had 4.10 gears and 14" tires. This will make your speedo read slow compared to actual speed. Consider checking with a speedo shop for an adapter to correct the reading. Or if you have a tach, you can judge speed off the rpm, just like they do in Nascar.
