...This crankshaft photo comparison was provided by David Glenn. The photos show us a "standard" 66mm crankshaft compared to a "performance enhanced" or "modified" crank. According to information David Glenn was able to researched (factory supplemental manual for the 906E-type 901/21, the regular 906 Owner's Manual and a full set of homologation papers), this "performance" crankshaft is the same as the one originally used for the homologation of the 906 cars. http://forums.pelicanparts.com/showthread.php?s=&postid=1582616#post1582616. Take a look...

...BTW, this crankshaft has been in storage for over 30+ years by a prominent Porsche mechanic and not one that was recently sent to a machine shop for performance enhancements.