Rahmen aus dem Inventor 11 Rahmengenerator lassen sich nicht im Inventor 2008 Gestellgenerator ändern
Das ist lt. Autodesk “as designed”
Issue
When you migrated frames created in Autodesk Inventor® 11 to InventorTM 2008, they were transformed into regular Inventor parts and assemblies, and you could not edit them using the Frame Generator tools.
Solution
Currently, this behavior is as designed. The migrated assemblies are fully editable using standard InventorTM tools and will be updated when parent geometries are changed. However, Frame Generator tools, such as End Treatments, cannot be used on legacy frames at this time. Support for legacy frames will be included in future releases of Inventor.
http://usa.autodesk.com/adsk/servlet/ps/item?siteID=123112&id=10036152&linkID=9242018

Tja, leider werden die Längen der Profile nicht mit geändert, also das benutzerdefinierte iProperty für die Länge…