NOTE : There were 2 different switches and linkages used in K45 and K5-A. Make sure yours looks like the photos. Also fitsK5 -A. This has the long bow shaped spring. If your mixer has the short flat spring you can use it in place of this one.
VINTAGE Speed Control Plate for KitchenAid K45, K5-A, 4-C, 3-C, K4-B mixers
Whirlpool Original WP9706648 OEM Genuine KitchenAid Stand Mixer Speed Control
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KitchenAid W10487697 Mixer Speed Control Assembly 120 Volt