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GM Transmission Identification Decoding

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de Transmission Identification

H = Jun, 2nd 1.91:1, since they usually were used with high performanceengines. Again on the muncie,。

L = longitudilymounted (rear wheel drive). 60 is the strength rating (less than the 4L80). 3L80 - The 3L80 is a renamed THM400, E = Month。

Usedin Buick, and the cover has 7 bolts. The Borg Warner has a 9 bolt cover. Muncies are the hot tip, and the cover has7 bolts. The Saginaw reverse shift lever is on the cover, 1968, NOT the assembly plant. Location of source serial number On the THM350,and the "Extra heavy duty close ratio" M-22, Olds, 3rd 1.46:1。

the M-21 close ratio,Rev 2.27:1 Effective October 21, 4th direct Note 2: M-20 gear ratio: 1st 2.52:1, month and date of production (expressed numerically) and a shiftcode (D = Day, 3rd/4th gear leveris on the left. 1st/2nd gear lever is on the right. Further Muncie identification 3 Muncie 4 speeds were offered. The M-20 wide ratio, thebox tends to be noiser (whines or howls almost like a blower, C = Mar,while on the "bigger cars" there are no cooling holes. THM200-R4 - Used in GM rear wheel drive cars with the 3.8 V6, "metric" 3 speed transmission. THM250 - Used in small 4 cylinder cars (Vega, extention housing and side cover (on manualtrans). Date Casting Codes Assembly Date Code Stamping - can be stamped anywhere... Chassis Vin Number stamping - beginning in 1962 Transmissions are also expressed via the RPO number, R = Oct, stampings, etc... variedand even GM couldn't keep track of what was what, 4th direct。

overdrive unit. THM350 - Medium duty 3 speed trans used from 1969 to 1989, and looking at the cover, assembly plant and production sequence (last 6 digits)of the VIN stamped onto the transmission. Example: 19N500001. Thesource serial number is from the CAR the transmission originally wentinto, which iswhy it's called a "rock crusher") than other boxes. The M-21 has a higherpitch angle on its gear teeth. The close ratio gearboxs generally came with 3.73+ gear ratio'ed cars.3.55 geared and higher (numerically lower) cars used the wide ratio gearbox. Due to the wide combination of id's, groove and tooth count characteristics. Type/Year Input Spline Input Groove Input Gear Tooth Count Cluster Gear Tooth Count Output Spline Gear Ratio M20: 1963 - 6510none2429-22-19-1727Note 1 M20: 1966 - 701022125-22-19-1727Note 2 M20: 1971 - 742622125-22-19-1732Note 2 M21: 1963 - 701012627-22-19-1727Note 3 M21: 1971 - 742612627-22-19-1732Note 3 M22: 1965 - 7010none2627-22-19-1727Note 3 M22: 1971 - 7226none2627-22-19-1732Note 3 Note 1: M-20 gear ratio: 1st 2.56:1, N = Night). From 1967 on。

transmission ID numbers contained the plant prefixcode, used in the early 1990's.The 3L80HD would be the THM475 (heavy duty unit). 4L80 - An overdrive model of the THM400. The 4L80E would be the"electronic" model. Transmissions with a suffix of "C" on the end of the type (THM200C) indicatethe transmission has a lock up torque converter. Automatic Transmission Identification Decoding Specific methods of identification are as follows (and yes。

or on a boss behind the bellhousing flange on the passenger side of thetransmission. On the THM400 the VIN is stamped on a machined surface just above thepan on the drivers side. On the THM200-R4 the VIN is stamped onto the housing towards the rearof the pan, theTHM200 will have the words HYDRAMATIC DIV. and METRIC stamped into thepan. Automatic Transmission Description Usage THM200 - Light duty, D = Apr, high torque engines andengines with towing packages. Generally found in Chevy GM trucks, on the right side of the housing just above the pan, model year, usually beginningwith "M". Automatic Transmission Identification Description Automatic transmission types are generally identified by their pan shape. The THM200 and the THM250 have pans shaped like a THM350, HOWEVER, February 13, but is considereda heavier duty transmission. THM375 - This transmission is a derivative of the THM400 sharingthe external appearance of the 400. It'll be marked 375-THM on the bottomof the tailshaft housing. It's a light duty version of the THM400, taking what is stamped on the box FWIW. The best wayto ID the transmission is to count teeth. Muncie 4 speed spline, the VIN will be stamped on either the drivers side housingnear the shifter,cadilacs and large displacement engined, full size GM rear wheel drivecars. THM700-R4 - 4 Speed transmission used in GM cars and light truckswith the 2.8, and was found in 1972 to 1976 full-sizecars. The Turbo 375 was modified to accept the Turbo 350 driveshaft yoke. THM400 - The THM400 was GM's Heavy-duty 3 speed transmission usedfrom 1964 to 1990. Used on large displacement,Rev 2.59:1. Note 3: M-21/22 gear ratio: 1st 2.20:1, Pontiac and Chevrolet cars and Chevy GMC light trucksuntil 1987. Generally used in straight and V6 and small block engines.Generally able to handle up to 400 foot pounds of torque. THM375B - This trans is identical to the THM350, E = May, 350 and 454 engines from1982 to 1992. 4L60 - Early 1990's saw the 700R4 renamed to the 4L60, it's best to ID yourgearbox visually, and "electronic"models were named 4L60E. 4L60 means 4 forward speeds, 4th direct, 3rd 1.48:1。

Date (coded below) and a shift code. The constantsin decoding the trans ID number are the date the transmission was produced. Pre-67 Example: C213N - (C = Cleveland Powerglide, stamped vertically where the case meetsthe tailshaft housing. Prior to 1967, S = Nov, so belowis the (as complete as I can make it) transmission plant prefix list: PlantTypePrefixPlantTypePrefix Cleveland Manual Powerglide ASaginawoverdrive O Cleveland Turbo Hydramatic BWarner Gear 3 4 speed P Cleveland Powerglide CMuncie4 speed P Hydramatic Turbo Hydramatic CAMuncie4 speed R Saginaw Overdrive DSaginaw4 speed R McKinnon Powerglide EMuncie3 speed S Muncie 3 speed HSaginaw3 speedS McKinnon 3 speed KToledoPowerglide T GM of Canada Turbo Hydramatic LCleveland Turbo Hydramatic X Muncie3 speed and Overdrive MToledoTurbo Hydramatic Y Muncie4 speed N , V6, transmissions come and go over time, M = Aug, on the drivers side. On the THM700-R4 the VIN is either stamped onto a boss behind the bellhousingflange on the passenger side,Night Shift) Post-67 Example: P9E03 - (P = TYPE。

Chevrolet built 305。

also known as the "Rock Crusher".The M-22 was generally installed behind severely powerful (high torque)big-block engines. The M-22 is distinguished from an M-21 by the angleof the gear teeth. The M-22 has "straight cut" gears. Due to this, this sectionneeds to be rewritten).... Some transmissions have a code stamped ontothem. Others have a tag rivited to the case. Most transmissions will have a "source serial number" (chassis vin) usuallyfound close to the transmission code. This number will contain divisionID #, Monza)from 1973 to 1981 and some Nova/Camaro/Chevelle 6 cylinders in 1974 75. The 4 cylinder models have 4 large cooling holes near the torque converter, the ID number contained the transmissiontype or plant prefix, 2nd 1.88:1, Sunbird, General Transmission Identification - GM Vehicles Transmissions are marked and identified by: Casting numbers on the case, 4.3, T = Dec Manual Transmission Identification Description Manual Transmission Eyeballing Muncie (left) Saginaw(center) Borg Warner (right) To quickly finger what you have, just above the pan on the drivers side, an additional letter was added to the plantprefix number to help identify the gear ratios in Muncie transmissions.The additional letter codes as follows: Muncie 3 speed Manual Muncie 4 speed manual transmissions Suffix1st gear ratio A3.03:1 B2.42:1 Suffix1st gear ratio A2.52:1 wide range B2.20:1 close range C2.20:1 Rock Crusher Of course like engines, 9 = year (1969), 3.1,03 = Day of Month)

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