Check the listing for details. NEW Nodular Cast Iron Ford 9" LSD 3rd Member 3.70 Gear 31-Spline 1310 C23404-31. Condition: New. Listed at 899.99 USD. These Ford 9 inch third member assemblies feature a limited slip differential available in 31 spline axle shaft configurations. The clutch style posi-traction unit is a proven combination and a better alternative for street driven cars vs the more expensive locker and spool options that are often overkill and not nearly as smooth on the street. It features heat treated spyder gears and spring loaded clutch pack with improved grip over OEM design. This unit is based off the proven original limited slip design with upgrades for a long lasting combination. The ring and pinion are made of 8620 Chrome-Nickel-Moly Steel. CNC machined from high quality forgings to our exacting specifications and then heat treated to obtain high impact and durability. Then lapped to allow for correct tooth contact and smoothness and for use in the performance market. Ride Right Designs Nodular Cast Iron Ford 9" 3rd Member Clutch Limited Slip Differential3.70 Gear 31 Spline 1310 Short Yoke Anodized Drain PlugBPC-420279lbs Also offered in a 3.50, 3.89, 4.11 & 4.56 gear