The 12-bolt and 9-inch rears are actually more similar than ... but the 12-bolt generally uses the smallest, 1310-style U-joint. Factory axles come in a 30-spline configuration and slide into ...

Some have argued that GM's 12-bolt axle has some performance benefits (primarily less frictional loss) compared to the Ford 9-inch, but even ... a 1350-series U-joint yoke, and a cast-aluminum ...

The debate within the debate has long been GM 12-bolt versus Ford 9-inch. In truth the GM 12-bolt is a far more efficient axle than the Ford because it consumes less energy. The reason for the 12 ...