GM SM465 4-Speed Manual Transmission Bearing & Synchro Kit

This is the bearing and synchro kit for tearing down and rebuilding a GM SM465, the cast-iron 4-speed granny-low manual behind the small block and big block in 1968-1991 Chevy and GMC C/K trucks, Blazers, Suburbans and 3/4- and 1-ton work trucks. It carries the deep 6.55:1 first gear that makes these boxes worth saving, and when one starts howling, grinding into a gear, or leaking at the tailshaft it is almost always worn bearings and synchro rings rather than the gears themselves.

The kit covers every rolling element in the case: the input (front) bearing, the output/mainshaft bearing, the countershaft (cluster) bearings and thrust washers, the pilot and reverse idler needle bearings, plus all the gaskets, the input and output shaft seals, snap rings and the small parts you throw away on a teardown. It also includes the 3-4 synchronizer blocker rings, so you replace the worn synchros that cause grinding on the shift instead of reusing them.

This fits 1968 and newer SM465 units with the cast-iron top cover and the 0.68 inch wide input bearing, and the box includes the two PTO side covers gaskets for the truck cases. It does not include gears, the synchro hubs or the shift forks; reuse yours if they measure good, and inspect the cluster and gear teeth before reassembly. Bench-rebuild it on a clean surface, set the shaft endplay per the SM465 service specs, and this brings a high-mileage 4-speed back to quiet, clean-shifting service. Ships from the USA; handling in 1-2 business days.