RTS M80 Differential, Gear Ring and Pinion 3.90:1, For Holden Commodore V8, VT Series 2, VX, VY, VZ, Ford Falcon FG Non Turbo XR6 4.0L - RTS-M80-390Part Number: RTS M80 390 RTS ring and pinion sets are manufactured to exceed OEM specification that are required for todays modern performance vehicles. The design, tooling, material selection and heat treatment recipes are all controlled by the RTS manufacturing factory to produce a cost alternative ring and pinion set that does not sacrifice quality. They are available in a wide variety of gear ratios for your modern Holden Commodore or Ford Falcon