Here is the answer from an article done by Frank Badalson. Lots of information!

http://roadtrip.yearone.com/2010_07_01_archive.html

And so the search engine will pick it up to help someone in the future:

Fender Tag Code for an E63 "69 383-4 manual trans" matches the Engine Assembly Code of 925 which will also be on the passenger valve cover.