This rubber bushing mounts the suspension rod that supports the gearbox assembly. It isolates vibration between the rod and the gearbox housing, reducing transmitted noise and shock loads. A worn bushing allows excessive rod movement, which can misalign the gearbox input shaft and cause driveline vibration. The manufacturer specifies this bushing for gearboxes that use the older-style suspension rod; gearboxes fitted with the newer rod require a bushing with a different inner diameter. On replacement, inspect the rod for wear and replace the bushing only with the correct version for the rod type.