any info on a 292 and 4 speed out of a 71 c10 (it is related to my 63 c10!)

[neverwinter]

hi all - i recently came upon a 72 c10 that i can use the rear axle in as a swap for my 63 to get better gears and 5 lug wheels. i really just wanted the axle but he is willing to sell the entire frame from radiator back including a 292 I6 with a floor shift 4 speed trans. i have a 48 chevy fleetmaster that i was considering putting a T5 behind the 216 over the winter.

what i am wondering is what kind of trans this is? he said its a 4 speed. i would assume since it is in a pickup that its a 3 speed with a granny gear? is this correct? id also assume that if the 4 speed in the truck can move the truck down the road then theoretically i could us ethe 292/trans in my 48 (i know i need motor mounts, open driveline etc). he has the starter, all wiring etc (i would have to do something with the 48's 6v system).

i guess i am just trying to sort if the whole thing is worth the asking price. i will def use the rear end and figured i could sell the front end parts to someone here doing a disk swap on an older truck ata a fair price to help them get going. is the 292 a bunk engine? again this will go in a 2 door 48 fleetmaster - not looking to go 100mph lol.

thanks all
- jason

[1963c-10]

The four speed is most likely the muncie sm420 or the saginaw 4sp. Pics would help identify it.

[1963c-10]

GM Muncie SM420 Transmission
The SM420 is an impressive, heavy-duty truck transmission designed for and used in ½, 3/4, 1 and 2 ton trucks. The SM420 was made by General Motors from 1947 to 1967. Military specification versions were made through the early 1980s. The SM420 is found in GM trucks, busses, heavy equipment and various military applications.

The "SM" in the transmission's designation stands for Syncrho-Mesh, in the tradition of other GM gearboxes, though we have heard that it may refer to Stewart - Muncie, a merged transmission division of GM.

Features
The SM420 is a top loaded, top shifting truck style transmission. It enjoys the lowest compound gear of all the common truck transmissions at 7.05:1 and as such it is a popular choice for those wanting a very low crawling gear.

The SM420 features a power-take-off (PTO) port on the driver's side of the case.

The SM420 is fully synchronized in the second through fourth gears. All gears are helically cut except first and reverse, which are spur gears.

Identification
The SM420 transmission is 10.7 " long and features a cast iron top cover that is retained by eight bolts and a main case of cast iron. The case itself has a prominent bulge on the passenger side in order to house the reverse idler gear. Later versions had two horizontal ribs cast into the passenger side of the case.


The common GM SM420 has a 1-1/8" diameter, ten spline input shaft that has a stick-out of 6-1/2" from the front face of the transmission. The pilot tip is ~19/32" in diameter. The front bearing retainer flange measures 4-11/16" and the bearing retainer tube is 1-3/8" in diameter. The front bolt pattern is the consistent GM Muncie / Saginaw four-bolt pattern as found on GM bellhousings and transmissions from the 1940's through the 1990's.

The SM420 most commonly has a large, 10-spline output mainshaft for both 2wd and 4wd versions. Some fairly rare 2wd models (likely the 2-ton versions) featured a 35-spline and a male threaded output. These versions also have a rare, 22-spline first gear journal, instead of the usual 11-spline "skip-tooth" journal.

The last year of the SM420 (1967) had a backup light switch installed in the top cover to meet that year's federal mandates.

1947-1953:
No ribs on the case
Grooved worm on the input shaft instead of neoprene seal
Synchro rings all differ from each other. 1st-2nd synchro ring is bronze
Weep hole at 6 o'clock on the bearing retainer snout
Six digit casting number on the case, usually like "59xxxx" e.g., 591665.
1954-1963:
Same as previous but uses a neoprene input oil seal
No weep hole at 6 o'clock on the bearing retainer snout
1964-1967: Same as previous except
1st-2nd synchro ring is aluminum and 3rd-4th synchro rings are identical to each other
Seven digit casting number usually like "37xxxxx", "38xxxxx" or "39xxxxx"
1968-1981: Military Con-Diesel version. Features the strongest case and optimized internals. Usually equipped with unique top cover, but can be converted to standard top-shift control.
The SM420 features a conventional "H" shift pattern, with reverse being towards the left side, and down

[1963c-10]

The 292 was a very stout engine, had alot of torque and can drink gas.

[shawno72]

Well if it's an original 71 setup wouldn't it be a different trans? Just asking cause I dont know.
Posted via Mobile Device

[1963c-10]

Your correct, didnt pay attention to that. Should be the sm465
The SM465 is an outstanding, heavy-duty truck transmission designed and used in ½, 3/4 and 1+ ton trucks. The SM465 was made by General Motors from 1968 to 1991. They are found primarily in GM and Chevrolet trucks, Blazers, Suburbans and many other models falling under the 1/4-ton to 1-1/2-ton platforms.

The 465 is an intellegently designed and very well-built transmission and remains easy to locate and generally inexpensive to buy and maintain. The strength, relatively short size and the gearing of the transmission make it a good choice for a variety of on-road and off-road situations. It has a very good set of road manners contrasted by its enormous off-road brawn.

The "SM" in the transmission's designation stands for Syncrho-Mesh, in the tradition of other GM gearboxes. It is also referred to as the CH-465 or CH465 by factory literature.

Identification
The SM465 is a top loaded, top shifting truck style transmission. This transmission is 12 " long and features a cast iron top cover that is retained by eight bolts. The SM465 case is of *cast iron. The case itself is generously ribbed both vertically and horizontally.

The SM465 has a 1-1/8" diameter, ten spline input shaft that has a stick-out of 6-1/2" from the front face of the transmission. The pilot tip is ~19/32" in diameter. The front bearing retainer flange measures an unusually large 5-1/8" in diameter and the bearing retainer tube is 1-3/8" in diameter. The front bolt pattern is the consistent GM Muncie / Saginaw four-bolt pattern as found on GM bellhousings and transmissions from the 1940's through the 1990's.

Features
The 465 enjoys a very low compound gear at 6.55:1 and as such it is a popular choice for those wanting a very low crawling gear.

The SM465 features power-take-off (PTO) ports on the passenger and driver sides of the case.

The shifting pattern for the 465 is in the standard "H" pattern with reverse gear being to the right side, and down.

SM465 Versions
There are three principal versions of the SM465, each based on the era and configuration of the transmission. There is no known mechanical superiorities to either earlier or later versions.

Earlier SM465
The earlier era of the SM465 include the 1968 - 1978 transmissions. There were both 2wd and 4wd versions. Internally, they are identical to each with the exception of the transmission mainshaft. The 4wd version of this mainshaft (or "output shaft") has a 10-spline output with a 2-5/8" stickout and an accompanying 4wd adapter housing. The 2wd version has a 35-spline threaded mainshaft compatible with a driveshaft yoke, and accompanying 2wd style tailhousing.

Spline Misunderstandings Clarified

"More splines are stronger"

Not necessarily. Larger shaft diameters are stronger, and larger shaft diameters usually require a higher quantity of splines. However, the automotive powertrain industries migrated to more splines on shafts due to their ease (speed, cost, etc.) of manufacture - smaller splines being able to be roll forged instead of the larger splines having to be machine cut.

A 32 spline output shaft vs. a 10 spline spline output shaft is probably only minutely stronger, and a decision of use here should be driven more by compatibility than perceived strength.
Later SM465
The later era of the SM465 include the 1979 - 1991 transmissions. A minor internal change of the 1st gear bushing and thrust washer occurred, in addition to a change from a shorter 10-spline, 4wd output shaft to a 32-spline 4wd output shaft - coinciding with the change of bolt pattern in the New Process 205 transfer case from a figure "8" input bolt pattern to a round, six-bolt input pattern. This pattern was also found on the 208 and 241 chain-driven transfer cases.

Later 2wd style SM465's also incorporated the same 1st gear bushing and thrust washer change, but the 35-spline, yoked output remained identical.