All sizes shown on the website for Porsche Lifestyle products are EU sizes.

Complete 1991 Universals & Rear Axle Axle Shafts & Joints Parts List
Shortcode = 1991 Porsche 928 Base GAS 5.0 V 8 Transaxle Automatic 4 UNIVERSALS & REAR AXLE Axle Shafts & Joints