GM 12-Bolt Chevy CAR / TRUCK Ring Gear Spacer w/ Bolts - 12P 12T - 902A * Use when installing 4-Series Gears (4.11, 4.56, 4.88, etc) onto a 3-Series Carrier (3.08, 3.31, 3.42, 3.55, 3.73, etc) Thickness: 0.305" - 0.315" Diameter: 8.875" Ring Gear Bolt Diameter: 0.4375" * Fits Car & Truck Rearends