The rear hatch wiper arm is part number 928 628 610 05 and new ones are no longer available. I suggest contacting used parts vendors such as 928 International (
www.928intl.com) to obtain one.
Rich
Membership Chairman
Charter Member
1993 928 GTS Cover Girl
1987 928 S4
1979 928 5-speed rescue
1979 928 5-liter track beast