They resemble rabbits due to convergent evolution
Viscacha or vizcacha (UK: /vɪˈskætʃə/, US: /vɪˈskɑːtʃə/) are rodents of two genera (Lagidium and Lagostomus) in the family Chinchillidae. They are native to South America and convergently resemble rabbits
I would think chinchillas would be more closely related to squirrels, than to rabbits.