I don't know much about this, but I hear people talk about 10-bolt and 12-bolt, and 9" stuff all the time. Is this all in the axle, or what? What are all those numbers?

 

GM differentials or rearends are nicknamed 10 bolts and 12 bolts; this refers to the number of bolts holding on the cover plate. The 10 bolt rear has a ring gear that 7 5/8" diameter. The 12 bolt ring gear is about an inch bigger in diameter. Ford rears are nicknamed by the size of the ring gear; therefore a Ford 9" has a 9" ring gear. In general, the larger the ring gear the stronger the rear end is. This is only a generalization, other factors like the gear ratio, type of rear (i.e. posi, locker, spool), axles, etc also affect the strength of the rear.

 

Oh, okay. That makes sense. I kinda had an idea about the bolt thing, but I didn't know it was all nicknames and such. Thanks for clearing that up for me somewhat.