Differentials and main gears are critical drivetrain components found within the axle housing of both front-wheel drive, rear-wheel drive, and four-wheel drive vehicles. They allow wheels to rotate at different speeds during turns, preventing wheel bind and ensuring vehicle control. Main gears establish the final drive ratio, impacting acceleration and fuel economy. Differential assemblies utilize pinion, ring, and side gears, alongside carriers and clutches (in limited-slip designs), to distribute torque. Robust construction with hardened steel alloys is standard to withstand high loads and torsional stress. Variations include open, limited-slip, locking, and electronic differentials, each offering differing levels of traction control.