Specifications:Ring Gear Diameter: 8 3/4"Pinion Shaft Diameter: 1.875Ring Gear Bolts: 12Left Hand Threads: 3/8-24Pinion Splines: 10Cover Bolts: 10Tech Note: Both the Tapered Pinion “489” and Straight Pinion “742” gear sets can only be used in the respective housings. Housings are distinguished by the numbers molded into the casings near the driveshaft flange.