The man who installed the LSD on my car told me that BMW doesn't provide rings and pinions anymore .
BUT she still provides crowngears for old cars .
Here an example:

http://www.realoem.com/bmw/showparts.do?mo...hg=33&fg=10

There are 3 kind of crownset and the E60 has the 'big' one .

So .. How can I know what kind of crownset the 745i E23 has ?
Ok, I could order that part for only EUR 300 and hope it is the part I need . But it doesn't seem to me the best way to proceede .

If we will understand which part by old BMWs is suitable to the E60 we will be able to change final drive ratio with only $500 + the job, buying the part directly from the dealer .

Bye!