I believe the Tops switched occasionally between Levi, Lawrence and Obie. And throughout Flo's tenure with the Supremes, aside from "Popcorn", Diana was the singles lead but every year through Flo's exit, the girls switched lead singers and/or shared leads in the studio from time to time. Sandra Tilley recorded a lead with the Velvelettes. In addition to Smokey and Claudette trading leads, Bobby and Ronnie also sang lead sometimes too.