Allison 6 Speed Transmission Swap

ATS Diesel Performance is now offering a complete kit so that our Allison 6 Speed Automatic transmission can be installed behind the Cummins 5.9L and 6.7L Engine.

For those of you that are not satisfied with the Dodge automatic transmission behind your Cummins engine, the Allison 6 speed swap is an excellent alternative. Whether you are reversing up steep hills, towing at highway speeds, or just looking for increased reliability and power, you will find that the Allison LCT 1000 built by ATS is far superior to the factory transmissions offered by Dodge. At ATS, we have a few different upgrade options available.  Our 6 speed Allison Conversion Kit and Allison Transmission Package are a great alternative and upgrade for your transmission.  Our Allison Conversion Kit gives you everything you need to run the Allison LCT 1000 behind the Cummins, and our Allison Transmission Packages can handle everything from stock power to well over 1000 horsepower.  The labor is pretty intensive so we would definitely recommend either bringing the truck to us in Arvada, Colorado or we can refer you to one of our Certified Installers in your area.   Another option we have is our ATS built 68-RFE Transmission Packages.  We have plenty of options here as well that would put you into a better and more reliable transmission, for a lot less money than upgrading to the unbeatable Allison 1000 transmission.  Our upgrades and modifications to the 68-RFE give you the performance you need while being covered by up to a 5-year/500,000 mile warranty. Although the 68-RFE will not take the abuse that the Allison LCT 1000 transmission will due to its inherent small clutch packs, gear set, and case design, the ATS built 68-RFE is a fantastic option for normal applications where power doesn’t exceed 700HP. If you have an Aisin transmission in your truck skip this link and continue reading, otherwise, you can click here to check out our ATS built 68-RFE Transmission Packages.
  • Dodge offered three basic transmission designs behind the Cummins equipped light duty 2500/3500 pickup trucks from 2003 to 2018.
  • 2003 to 2007 Dodge 2500/3500 5.9L came with the 48-RE 4 speed automatic transmission
  • 2007 to 2018 Dodge 2500/3500 6.7L came with the 68-RFE 6 speed automatic transmission
  • 2007 to 2014 Dodge 3500 Cab and Chassis came with the Aisin AS-68-RC automatic transmission
  • 2014 to 2018 Dodge 3500 came optional with the Aisin AS-69-RC automatic transmission

While ATS offers rebuilt versions of these three transmissions using heavy duty upgraded parts, those transmissions do not offer all of the benefits of a fully built Allison LCT 1000 6-speed transmission.

Due to the nature of the Dodge 48-RE, 68-RFE, and AS-68-RC having very small shafts, gear sets, and clutch packs, the factory Dodge transmissions require very extensive modifications and expensive hard parts to marginally compete with a ATS built Allison LCT 1000. Dodge transmission upgraded parts include the hydraulic pump, clutch packs, shafts, and torque converter modifications to strengthen it to reliably handle the massive torque of the Cummins engine. Conversely, the Allison LCT 1000 6-speed automatic transmission comes from the factory with large shafts, clutch packs, and gear sets. This gives the Allison a direct advantage over the 47-RE and 68-RC Dodge transmissions. The 69-RC has similar size clutch packs, shafts and gear sets as the Allison, however, it does not have an ideal gear split so the 69-RC always seems a bit “clunky” and does not handle increased power levels well.

The number one failure in any transmission system is the torque converter. All Dodge and Allison diesel torque converters are about the same in size, and they are all under-designed. This means that they must all be upgraded to a multiple-disc platform to be reliable and hold any increased power over stock. When all costs are taken into consideration with regards to what it takes to upgrade all of the small and under designed components of the Dodge transmission, a conversion to the ATS built Allison LCT 1000 could be argued to be the most cost effective solution available on the market today.

Decisions, decisions…

There are a few questions you should ask yourself when weighing the decision of whether to go with an ATS upgraded Dodge transmission or to replace it with an ATS built Allison conversion:
  • Is your Cummins engine heavily modified, re-programed/tuned, have modified turbos, fuel delivery, etc…?
  • Do you tow extremely heavy loads for long distances?
  • Do you have over sized tires and like to abuse your truck?
  • Does your vehicle appear to be under stress with the workload you are subjecting it to?
  • If you answered yes to any of these questions you are a prime candidate for the ATS built Allison Conversion.
  • To learn more about how the ATS built Allison Conversion can improve upon your specific transmission click here.

The 48-RE transmission is very old technology that has been passed on for many years. It utilizes bands, hydraulic throttle valves, and governor pressure to control shift timing. The 48-RE transmission will never be a smooth-shifting transmission, or have the consistency of the newer designed transmissions.

The first three gear ratios of the 48-RE are evenly spaced, while fourth gear (overdrive) has a massive ratio jump. The big jump into overdrive creates a large RPM drop, making it somewhat unpleasant for towing. The lock-up torque converter was introduced as an afterthought. The already outdated low line pressure transmission makes it difficult to control the application of the converter clutch, which provides unpleasant torque converter application. If you’re looking to tow a trailer at a higher horsepower, the 48-RE transmission may not be the best transmission choice. Although the 48-RE can be upgraded to be extremely reliable and handle very high power levels, the shifting of an upgraded 48-RE transmission still has the feel of an old school 4 speed automatic of the past.

The 68-RFE transmission has a fantastic gear split from first through sixth gears, providing an almost perfect gear ratio change. The torque converter utilizes PWM technology, allowing for precise application of the converter clutch, which provides smooth torque converter application. Unfortunately, this is where all praise for the 68-RFE ends. The 68-RFE transmission was clearly designed to be the least expensive to manufacture. As a result, there are many elements that must be upgraded in this transmission to make it reliable and handle higher power levels. Even the transmission case is cheaply designed and must be reinforced with a large aluminum pan and the exclusive ATS 68-RFE case brace to keep if from cracking in half. The 68-RFE internals are merely larger versions of those found in the Dodge Caravan transmission that originally debuted in 1989. Chrysler used this basic design and adapted it to be used behind their gas engines, calling it the 545-RFE. Then, they made a few parts in the 545-RFE transmission a little larger, which eventually became the 68RFE that we know today to be used behind the Cummins. The 68RFE can be rebuilt with upgraded parts making it a great shifting transmission but it still has limitations because of the small clutch packs, gear sets, and shafts that make up the transmission. Similar to the 48-RE, the money spent to strengthen the internals of the 68-RFE is arguably better invested in the Allison Conversion. If you were to spend the money to upgrade the internals of the 68-RFE, you would still be left with a transmission that has clutch packs, gear sets, and shafts that are nearly half the size of those in the Allison.

For those that currently have a 2007 to 2014 Aisin AS-68-RC, upgrading to the Allison is the only logical choice. The Aisin AS-68-RC transmission suffers from many of the same shortcomings as the 68-RFE but also has additional unique issues. Currently there are limited hard part upgrades available for the Aisin AS-68-RC, and there are many areas that need to be addressed, not only for strength, but for longevity. Factory replacement parts are two to three times the cost of 68-RFE parts which drives the cost of rebuilding the AS-68-RC to an unreasonable level. For these reasons, ATS decided to focus our efforts on making the Allison 6-speed Conversion affordable for anyone that needs to replace their failed 68-RC.

In order to properly transplant the Allison transmission into the Dodge Pickup there are many which ATS addresses: How the transmission is adapted to the engine, transfer case, cooler line adaptation, manual linkage, fill tube, transmission electronic control system, and driveline modifications are the basics. The engine calibration also has to be changed to a calibration that will work with the Allison transmission. Without the changes to the factory calibration, when the factory transmission is not present, the ECM sees this as a fault and engine powder is de-rated. There are many tuning companies that provide custom tuning to recalibrate the engine, and this step will have to be done in order for the engine to run properly without de-rating. We can recommend the right calibration for your application, and the tuning company to use to get it done. What would be the best all around transmission for a person that tows, wants to use the power of their high horsepower Diesel, is looking for reliability above all, and still would like to have the ideal shifting transmission? The Allison 1000 is the best option, and it’s now possible to reliably and affordably put it behind the Cummins engine! As great as the Allison transmission is, this does not mean you can take just any Allison 1000 transmission and put it behind the Cummins engine. The ATS Allison LCT 1000 addresses and fixes all of the stock Allison transmission limitations and downfalls. The great news is the Allison can easily and affordably be upgraded to handle a very high level of abuse and high horsepower while providing reliability and longevity. Other benefits of the Allison is that it learns your driving style, power levels, driving habits, etc., and the Allison TCM will adapt to them all, providing a smooth shift throughout all the ranges. Tap shifting capabilities and tow-haul are all still present as well. For the 6.7L Cummins you can use the factory shifter, and for older trucks you can purchase a new shifter, which can be installed in a matter of minutes and still has all factory functionality. Overall the Allison can handle more power, with more functionality and longevity than other transmissions. An Allison Conversion is a solid choice whether you want it for your daily driver, tow a lot or want to take your truck down the sled pulling track.

Allison Conversion Package:

  • Adapter Plate
  • Billet Flex Plate
  • Transmission Controller
  • Transfer Case Adapter Kit
  • Shift Linkage Kit
  • Dipstick Tube
  • Cooler Adapter Lines and Fittings
  • Transmission Mount
  • Analog Sensor CAN Controller

Allison Conversion Package expectations and costs:

  • Allison Install Kit – Everything you need to install an ATS Allison Transmission into you truck $5,500.00
  • Transmission - Estimated cost for an ATS Transmission assembly (Transmission, Torque Converter and Pan) is between $3,500.00 and $7,000, depending on which stage you need for your power level. All of the ATS transmission packages come with up to a 5-year / 500,000 mile warranty
  • Transfer Case – You should not have any additional cost or modifications associated with this part
  • Drive Shaft - Some driveshaft work may be required. Worst case is you will need to shorten one and lengthen one of each, front and rear drive shafts. You can consider an average cost of about $400.00 per drive shaft.
  • Installation - Estimated time to do the complete install if done be a professional is between 15 to 20 hrs.

In summary the Allison swap will cost you more than upgrading your factory Dodge transmission, and your truck will be down for about a week while the drive lines are being modified. In the end, the benefits will be well worth the extra money and time you spend on the upgraded Allison Conversion. Reliability, smooth shifting, more power to the wheels, being in the optimal gear all the time, better acceleration, responsiveness, less maintenance cost, and overall driving enjoyment are a few of the reasons the Allison 1000 6-speed Conversion is so popular.
Regardless of your needs, call and talk to on of our sales technicians for specific recommendations and pricing for your application.

ATS Diesel Performance

5293 Ward Road

Arvada CO, 80002


Business Hours: 7:30a - 5:30p

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