Well....I have to say something about opening the case...
In a 1992 964 w/115K we found the main bearings are OK, but had a #5 rod bearing
starting to fail - photo below. The Intermediate shaft bearings were worn as others have said
happens most of the time and needed replacement.
We needed to micropolish and magnaflux the crank along with balancing the crank and rods and pistons. The rods were also reconditioned and big hole recut. ARP rod bolts were installed.
IMHO...all used engines are unique situations...just sayin'
Regards,
