4.30 Ratio 8.75in Mopar

The Richmond 4.30 Ratio 8.75in Mopar ring and pinion kit is a high-performance differential gearing solution engineered for Mopar 8.75-inch rear axles. This 4.30 ratio ring and pinion set delivers numerically aggressive gearing optimized for improved acceleration, engine braking, and low-speed torque multiplication—making it an essential upgrade for street performance, off-road recovery, and towing applications where quick response off the line is critical.

Built on a 489 case with 10-spline pinion design, this ring and pinion kit provides reliable load-carrying capability and compatibility with factory Mopar 8.75-inch axle assemblies. The 4.30 gear ratio trades top-end highway cruising efficiency for substantially lower rpm at any given speed—a trade-off that appeals to drivers prioritizing acceleration and load response over fuel economy. Installation is straightforward on the Mopar 8.75 platform, and the kit format includes both the ring gear and pinion together, simplifying the upgrade process and ensuring factory-matched geometry.

This configuration is favored by vintage Mopar enthusiasts, muscle car restorers, and off-road operators running factory 8.75 rear ends who demand better off-the-line performance without a full axle swap. The 4.30 ratio sits in the sweet spot between extreme aggression and daily usability, offering noticeable improvement in responsiveness while remaining compatible with automatic and manual transmissions. Weight of 16.05 lbs reflects a durable, solid steel assembly built to withstand the demands of upgraded power and heavy-duty operation.