1966 Ford Thunderbird Ring and Pinion Set Ford 9 in. - Ring and Pinion Set - 4.56 Ratio - 9310 Pro Gear - Oversized 35 Spline Pinion - Rear guaranteed to replace your current 1966 Ford Thunderbird Ring and Pinion Set Ford 9 in. - Ring and Pinion Set - 4.56 Ratio - 9310 Pro Gear - Oversized 35 Spline Pinion - Rear. 1966 Ford Thunderbird Ring and Pinion Set comes new OEM 1966 Ford Thunderbird Ring and Pinion Set aftermarket new 1966 Ford Thunderbird Ring and Pinion Set of remanufactured 1966 Ford Thunderbird Ring and Pinion Set Ford 9 in. - Ring and Pinion Set - 4.56 Ratio - 9310 Pro Gear - Oversized 35 Spline Pinion - Rear.