Richmond PRO Ring & Pinion Gear Set, 3.89:1 Ratio - RI79-0043-1RICHMOND 9" FORD 3. 89 PRO GEAR 35 Spline Pinion. Suit Ford 9" Part Number: RI79 0043 1 Richmond Gear Pro Gear ring and pinion sets take it a step further. The gear sets are designed for race use only where hard launches and severe heat cycling occurs. They're made from a softer, more malleable 9310 steel alloy to be more resistant to breakage under harsh racing conditions. These gears feature an outstanding rotating weight loss of up to 6 pounds,