Cylinder head stud part number supercession
 

Dealer shows cyl head stud 993.101.170.51 is superceded by 993.101.170.54 and/or 993.101.170.53.

Anyone have any idea what the difference is between 993.101.170.54 and 993.101.170.53?

No way of knowing for sure without the Porsche drawing, or being able to identify some changes by inspection. 993 is of course the model it was introduced on. 100 means it is engine related. 101 is the page in the PET catalog that the part is shown. 170 is a system generated number that is for this specific part. 53 is the revision number. It can be anything. Some people have stated it is a material change, a supplier change or other. In fact, it can be anything that is different from the previous version. The main point though is that if it is a revision, it has to function just like the previous revision, otherwise the "170" portion of the number has to change.

Excellent and accurate description of the numbering standard.

Cheers

As noted, sometimes part numbers change based on supplier.
The biggest concern in the world of parts sourcing is the inconsistency of standards.
Porsche makes very few parts. They out source everything.
As we've seen recently with timing gears, even Porsche can source inferior parts.

Could just be the packaging, 10 vs 12. Packaging label is usually called out in the drawing.http://forums.pelicanparts.com/uploa...1615178351.jpg
http://forums.pelicanparts.com/uploa...1615178372.jpg