70 dart turn signal cam question, what the heck?

Ive looked for a thread, cant seem to get the answer.
QUESTION: I have ordered a replacement turn signal switch for my 70 dart. Everything works electronically, however the "cam" for the turn signal cancel has a wider mouth than my factory unit. All of ther replacement switches seem to come with the larger yellow cam, not my smaller white one. perhaps I have the wrong application. I do NOT really want to tinker with switching the cam if i don't have to.. Am i not ordering the correct replacement??

Thanks ...kevin