When it comes to muscle cars, each of the Big 3 had their top dog rear axle. Their answer for the biggest and baddest engine of the day. For GM, it was the 12-bolt. A Salisbury style axle with a good-sized ring gear and beefy axle tubes. Ford used its 9-inch. A sheetmetal center with a drop-out style differential and ring-gear carrier. And for Mopar, it was the Dana 60. A Salisbury design so big that is was only found elsewhere in 1-ton trucks.
As with everything muscle car related, the rear axle topic is always good fodder for brand loyalists to banter about. Thanks to several aftermarket companies, however, you can now order a brand new 12-bolt or 9-inch to bolt right into your GM muscle car. This lets a GM guy cross enemy lines and genuinely consider which is better.