E30 Zone

Hi, first post in a while. if anybody knows the answer to this question i will be amazed! does anyone know the difference between the -09/99 and the 09/99- gearboxes on the e39 m5. i imagine that it is just ratio's but does anyone know for sure? any help would be much appreciated!

i believe the difference in the two boxes is to do with the
gear identification switches
dont hold me to it though

glenn