Linkage arm that attaches to the windshield wiper motor that is unique to the 1971-73 Mercury Cougar and Ford Mustang. These are marked 1Z, among other things the slot is specifically indexed for the 1971-73 Cougar and Mustang application. This is basically an installation kit that includes: linkage arm, flat bushing, wave washer, and nut. The order of installation is flat bushing, wave washer, linkage arm, and lastly the nut.