Dariel Díaz

In my research I conclude that it is a 1956 model. I want to know if I can change the pinion and the gear ring to obtain ratio 3.9 or 4.1. And how to know that I am looking for why there are many parameters as if it is 10 or 12 bolts if it is 8.5; 9.25; 9.5; ect inches ... attached pictures of the differential. Thank you

Hello.. Lower Control Arm Buick 55 Super has the same large that Special or Century ??? I think that Super and Roadmaster have a larger control arm but I'm not shure. Thanks. Sorry for my english.