General Guide to Finding the Perfect Transfer Case for Your Needs

A transfer case is the heart of the four-wheel-drive system found in your rig. That means you want one that delivers amazing functionality and exceptional dependability. However, with so many transfer cases available on the market, it can be difficult to determine which type is best to meet your needs. Luckily, there’s an answer to better understand your options.

Below is a list of the best transfer cases for a 4×4 system, so you can find the ideal option that meets your needs. Keep reading to learn more!


transfer case
A transfer case is essential for fun off-roading.

Transfer Case Types

Before running out and splurging on a new transfer case, you must understand the details of each unit to ensure it fits your requirements. The transfer case types include:

Atlas II

The Atlas II transfer case is considered legendary and has become the second-most popular option for those in the Top Truck Challenge. Approximately 30% of competitors had this transfer case in their rig from 2004 to 2006. This rugged one-piece case is constructed from 356-T6 heat-treated aluminum alloy, so the part can take a beating. Inside the case are strong helical-cut gears held by needle bearings that match the strong 8620 shafts, which are then supported by larger bearings.

The Atlas II case is available with two front output shafts and 11 input-shaft splines, which equates to a 26- or 32-spline configuration. Additionally, the case is available in six low-range ratio options, with one of the best choices being the 4.3:1 since it’s the most well-rounded ratio.

Dana 20

Cased in cast iron with a 2.0:1 low range ratio, and gear-driven, the Dana 20 was found across countless vehicles including Fords, Chevys, and Jeeps. It was the successor to the Dana/Spicer 18, so some parts overlap with the 20. However, unlike the Dana 18, the 20 delivered a more direct driving method in the high range.

Dana 300

A descendent of the Dana 20 is the Dana 300, which is a strong transfer case featuring helical-cut low-range gears, which the Dana 20 lacks, and equates to a nice and quiet low-range operation. This transfer case was mostly found in ’80-’86 Jeep CJS, as well as the ’80 Scout. The 300 was built with a cast iron and gear drive, making the total weight around 85 pounds. The 300 also boasts a 2.62:1 low-range gear versus the 2.0:1 found on the Dana 20. This transfer case was the last cast-iron, gear drive option installed by Jeep.

Model 18

The Model 18 transfer case was produced for over 30 years, which speaks volumes about its dependability. Constructed from cast iron, this two-speed, gear-driven, offset-drive case can be found in ’40-’71 Jeeps and several international truck brands. As a result of being in the market for so long, several Model 18 versions exist, with the most sought after being the large case in the ’66-’71 vehicles, which includes the V6 Buick engine with a T-14 or T-86 transmission.

The Model 18 can withstand more power than originally designed, which it manages without any complaints. Since the Model 18 is a side-drive case, the intermediate gear is always taking the brunt of the load. This could result in the intermediate shaft and bearings being prone to wear and tear. Since the Model 18 was phased-out decades ago, it can be difficult to find units.

NP205

The NP205 has a legendary ruggedness, which this claim is reinforced by the fact that 16 out of 30 Top Truck Challenge competitors between 2004 and 2006 utilized this transfer case in their rig. The 205 is a gear-driven component that was built into standard International, GM, Ford, and Dodge trucks. With a low-range ratio of 1.96:1 and a length of 14 inches, this transfer case is available in many versions with varying bolt patterns and input shaft configurations.

Also, married, and divorced versions exist with an endless number of aftermarket upgrades which make the NP205 significantly better. Some of these upgrades include the Off-Road Design Doubler, which combines the gearbox section of the 203 with the 205 cases, resulting in a 4.0:1 ratio, a Klune underdrive, and twin sticks.

T-136-27

The T-136-27 was originally found in 2.5-ton military 6x6s, so it’s a monster component that weighs around 400 pounds! The housing is gear-driven and constructed from cast iron. This unit boasts a 1.98:1 low-range ratio and is considered a divorced part. Shifting is accomplished via air, which only requires around 36 psi. Since then its launch, this transfer case was also adopted by monster truck drivers searching for a unit that can withstand the constant abuse of 66-inch tires.

It’s important to note that an earlier version of the T-136-27 exists and is visually similar. This version was called the T-136 and is not desirable due to the undependable front-drive spray and its mechanical shift. Therefore, when you go searching for the T-136-27, ensure it’s not being confused with the T-136 or you will be greatly disappointed.

13-56

The low range 13-56 transfer case was mostly used in Ford F-Series and Bronco trucks between the years ’87 and ’96. Although it has an aluminum chain drive and housing, this transfer case is incredibly durable, and Ford used it in countless models including the 460ci V-8 and 7.3L diesel engines with incredible success. It does succumb to some normal wear and tears on the chain and bearings, but that’s common in any transfer case.

The only real Achilles’ Heel for this component is the oil pump, which can become loose and rotate causing lubrication loss. Some prepare for this issue by modifying the case to include a sheet metal screw through the pump and into the housing unit. Furthermore, some experts report that since the 13-56 mounts into the transmission, it is further susceptible to axle wrap damage, so it’s important to control axle wrap or stabilize the case.

Many transfer cases are available for 4×4 and AWD vehicles, but without some type of guideline, it can be difficult to understand which type is best to meet the needs of your vehicle. Reman Transmission has a wide variety of transfer cases for sale for that very reason, https://reman-transmission.com/transfer-cases. These are some of the best on the market that you should consider for your rig!

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Author: Luke Wilhoit
Luke Wilhoit is an experienced blogger who has written professionally for websites in the automotive, travel, and financial industries. When Luke isn't working, he’s probably fishing, snowboarding, hiking, or doing something enjoyable outdoors.

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