GM 14-bolt (10½-inch ring gear)
The GM 14-bolt came in both a 9½-inch ring gear and a 10½-inch ring gear, and they're totally different animals. The latter is the more desirable, and its only resemblance to the 9½-inch is the number of cover bolts.
Application: Rear.
Type: Semi-floating.
Spline count: 30, 33.
Factory ratios: 3.23:1 through 5.14:1.
Maximum tire size for stock axle with 10½-inch ring gear: 44-inch.
Strong point: It features a removable pinion support and a pilot bearing at the end of the pinion shaft for added strength.
Weak point: The left-side carrier cap is known to break through the bolt hole.
Junkyard jewel: Find one on a '73-to-current ¾- or 1-ton Chevy truck. The newer the axle, the better.
Building secrets: Replace the Gov-Lok diff with an aftermarket unit.
Aftermarket alternatives: Custom Differentials.