GM 8.875in.12-Bolt Ring Gear Spacer by Mr. Gasket GM 12-bolt 8.875in. ring gear; Bolt hole diameter .437in.; Spacer thickness .305in. to .315in.; Stamped Steel; Blanchard ground to ensure parallel surfaces for perfect alignment; Kits are complete with spacer and bolts. Mr. Gasket Company Mr. Gasket Company GM 8.875 Inch12-Bolt Ring Gear Spacer by Mr. Gasket - 902A 902A Ring Gear Spacers