Muncie SM465 transmission

The Muncie SM465 is a heavy-duty, four-speed manual transmission built by General Motors for use in light and medium duty trucks from 1968 to 1991. The SM465 can be found in Chevrolet and GMC full-size trucks, Blazers, Suburbans, among other models. Some applications beyond one-ton pickup trucks came with larger input shafts. Favored by off-road drivers, the SM465 has a very low first gear suitable for rock-crawling. The SM465 has developed a reputation as a highly durable transmission. For the 1992 model-year, the SM465 was replaced in 3/4- and 1-ton pickup truck applications by the New Venture Gear 4500 transmission.

Muncie SM465
Munchie SM465 Transmition.jpg
Overview
ManufacturerGeneral Motors
Production1968–1995
Body and chassis
Class4-speed manual
Chronology
PredecessorSM420

The "SM" in the transmission's designation does not stand for Synchro-Mesh, contrary to popular belief. "SM" stands for "SAGINAW MUNCIE". GM literature also often referred to this as a CH465, referencing Chevrolet.

Gear ratios are:

  • First - 6.55:1
  • Second - 3.58:1
  • Third - 1.70:1 -Sometimes incorrectly listed as 1.57:1.
  • Fourth - 1.00:1
  • Reverse - 6.09:1

The SM465 features dual provisions for power take-offs. The 1988-91 versions have an aluminum top with improved shift feel. The 1985 and newer versions utilize a hydraulic clutch release, replacing a mechanical linkage in older versions. A common wear factor in the form of abuse leads to having to manually hold the gear selector in third. There have been three different output shafts for pickup trucks. Early four-wheel drive was a short 10 spline, late 4WD was long 32 spline, and all two-wheel drives were 35 spline. Early 4WDs came mated to New Process 205 transfer cases. The 1981 and later versions[1][circular reference] came with a New Process 208 if not a 205. New Process 241 was used behind the 465 starting in 1989 when it replaced the New Process 208 in the V-series trucks. The SM465 was the only manual transmission available for 1988-1991 R/V-series trucks and SUVs.

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