Question: what is the difference between a 10 and 12 bolt rear end?
Answer: First, the 10-bolt's pinion shaft diameter is 1.438 (25 splines) while the 12-bolt is 1.625 (30 splines) which makes the 12-bolt 13 percent larger in diameter and therefore stronger. ... The 8.2 uses a 28-spline axle (1.20 inches in diameter) while the 12-bolt uses a 30-spline axle (1.625 inches in diameter).