TNT Transfer Case
General Motors Transfer Case Models.
Re-manufactured Transfer Cases
TNT Transfer Case wanted to share some information about the different GM Transfer Cases available. Some of this information has been gathered from other 4×4 enthusiasts and professional mechanics that want to share their knowledge. We hope this information can help you determine which transfer case you need and any upgrades that might be available. We hope this might help in identifying the transfer case found on your G.M. Vehicle, (Including Chevy, GMC and Cadillac).
Let’s face it, sometimes SUV’s, 4×4’s and other Offroad vehicles, are a necessary part of life. Use your off road vehicle wisely. We replace all bearings, seals, fork pads, viscous (when the unit has them) and chains (chains are Morse and only Morse chains). Each Transfer Case is unique and specific to the vehicle. Please locate the identification tag on your transfer case and write down the Model & Assembly Numbers. These numbers are critical in determining the exact transfer case for your vehicle.
GM NP136 Transfer Case
The NP136 transfer case was manufactured with electrical shift encoder motors, this unit has two different drive ranges 2 high and 4WD, (run at reduced speeds). With the front output drop on the driver side. This unit has a 27 spline front output and utilizes a rear slip yoke. This unit has a couple of problems, it utilizes a viscous coupler clutch system that can fail. One way to recognize this failure mode is clicking sounds when turning on dry asphalt or concrete surfaces. Viscous coupler failure is attributed to excessive heat build up. The second problem is that the oil circulation pump on NP136 can wear a hole in the case, we provide a transfer case upgrade to prevent this from happening. Once you have a hole in the case fluid will be lost and the case will fail.
Usage: The NP136 transfer case was used in GM vehicles that include the GMC Safari Van (from 1999 and on), the Jimmy, the Suburban, and the Yukon Denali (only the Denali version is able to take this case) from the year 2000 and up. It is also seen in the Chevy Astro Van from 1999 and up.
GM NP149 (AWD) Transfer Case
The NP149 (AWD) transfer case was used in the GMC Yukon, Denali, Sierra 2001-2005. Cadillac Escalade Ext. Esv. 2000-2002.
Contact us with your VIN # or Model # (located on rear case half of transfer case) to insure we ship you the right transfer case for your vehicle. 27 spline Input Gear.
GM NP 207 Transfer Case
The NP207 transfer case was used in several GM and Chevrolet S-series vehicle applications.
Usage: S-Series Blazer from 1982-1988, the S10 from 1983-1988, the Jimmy J-series from 1983-1988, and the S15 Compact Truck from 1983-1988.
GM NP 208 Transfer Case
The NP208 transfer case is similar to the NP203 and NP205 cases, sharing a number of applications between them, though on the 208 the casing is made out of aluminum rather than iron.
Usage: Chevy Blazer, Suburban, and Tahoe from 1981-1988. Chevy pickups and vans from 1981-1987. GMC Jimmy, Suburban and Yukon and Full Size pickups 1981-1988.
GM NP231 Transfer Case
The NP231 was has a left side drop output and a low gear ratio of 2.72 to 1. This unit has 2WD and 4wd, combination of 2 high, 4 high, neutral and 4 low. Utilizes a 27 spline front output and a rear slip yoke. The NP231 can have issues with premature chain failure, caused by running on hard surfaces like concrete or asphalt, Run 4WD only on loose dirt, snow, mud, sand or grass as the different wheel speeds in turns can put excessive torque loads on chain and sprockets. The New Process (NP) 231 transfer case is one of the most common manually operated transfer cases found in all domestic 4x4s except Fords. The NP231 case, like the 207, is a found in S-series vehicle applications. Having an aluminum case and being driven by a chain.
Usage: the NP231 can be found in Blaze S-Series from 1988-1997, the S10, the S15 Series Jimmy and Compact Truck.
GM NP236 Transfer Case
The NP236 is chain driven. The NP236 is an Auto 4WD and electric shift. manufactured with left side drop output and has a low gear ratio of 2.72 to 1. The NP236 can have issues with case failure caused by the oil pump housing wearing a hole in the case Another problem associated with the NP236 transfer case is input and or output bearing wobble wearing out the case. Run 4WD only on loose dirt, snow, mud, sand or grass.
Usage: used in Chevrolet S10 Blazer and S10 Pickups. Chevrolet started using this transfer case in 1999 models.
GM NP241 Transfer Case
The NP241 is a solid, reliable transfer case and superior to the NP203 it replaced. But as they age, the drivechain can stretch. Also, the synthetic pads on the shift forks wear, causing intermittent problems when the forks do not stay in their intended position. Offered with both passenger and driver side front outputs. Input spline counts from 23 to 32. Versions were built for mechanical speedometer cables and for electronic vehicle speed sensors.
Usage: 1989-1999 Chevrolet Blazer, Suburban, and Tahoe, as well as the 1500, 2500, 3500 Truck and Van. GMC Jimmy, Suburban and Yukon and the 1500, 2500, 3500, Sierra and Full Size Van
GM NP243 Transfer case
The NP243 Transfer Case is commonly found in late 90s GMC and Chevrolet SUVs. Chevy used a NP241C and the GMC a NP243C transfer case. That is New Process, also known as New Venture. The main difference is that the NP243 is electronic shift, but not Autotrac or all-wheel drive, it is simply a push button activated transfer case with 2HI, 4HI and 4LOW. This system signals an electronic motor mounted to the transfer case to shift the transfer case, rather than a shift lever with mechanical linkage.
Usage: The NP243 was installed in General Motors vehicles starting in 1996, used in both 1500 and 2500 series pickup trucks, suburban, Tahoe and Yukon’s. These transfer cases are part time four wheel drive electric shift.
GM NP 246 Transfer Case
The NP246 case may seem identical to its previous model, the 243, it has the added feature of being more compatible with more engine sizes than ever before.
Usage: Full size Chevy Blazer, Suburban and Tahoe and the GMC Jimmy, Suburban and Yukon. 1998-2001 (GMC 2000). Chevy 1500, 2500, 3500 truck and Van. GMC Sierra 1500, 2500, and 3500, along with the Full Size Van the run was only 1998-2000.
GM NP261 Transfer Case
The NP261 Transfer case is used for more heavy duty applications, being reserved for mostly truck and van use. The NP261 transfer case was manufactured by New Venture Gear. The NP261 is chain driven, 4WD with manual shift. Left side drop output and has a low gear ratio of 2.72 to 1. Has a combination of 2 high, 4 high, neutral and 4 low. Some pickups are supplied with heavy duty (HD) and extreme heavy duty (XHD) heavy duty version with wider chains, sprockets and HD planetary.The NP261 can have issues with case failure caused by the oil pump housing wearing a hole in the case. A better option is to replace the rear case with the new design. Another problem associated with the NP261 transfer case is input and or output bearing wobble wearing out the case.
Usage: Chevy 1500, 2500, 3500 Truck and Van. GMC Sierra 1500, 2500, 3500,1500 and Full Size Van.
GM NP263 Transfer Case
The NP263 is a chain driven electric shift and part time transfer case. The output is on the driver-side with center rear output. There are three different versions of this unit the light duty “LD” , heavy duty “HD” and the extra heavy duty unit “XHD”. The 263XHD unit is supplied with most diesel versions, the HD version has a 6 pinion planet and utilizes a 1.5″ wide chain. The NP263 has a couple of design problems, the oil pump can wear a hole in the rear case half. We recommend using the upgraded rear case. The second problem is caused by heat build up, failure of the shift forks causing the plastic pads to melt and damage the range shift hub and sometimes cause shaft damage.
Usage: Chevy and GMC 1500, 2500 and 3500 pickup trucks, along with Suburbans from 2001-Up.
Get the replacement transfer case upgraded heavy aluminum rear case that fixes inherent weaknesses built into OEM (original equipment manufacturer) transfer cases that came with the vehicle you have. If your vehicle has one of the listed models, your transfer case may end up with oil leaks.