1999 Dodge Durango 48RE Automatic Transmission

You could have 700 horses steaming with muscle at the crank, but if you can't get the power to the ground, then all you have is an angry stable. When we first thought up this crazy idea of stuffing an 8.3L Dodge Viper engine into our '99 Durango, we knew that our transmission options would be limited. Since the six-speed that's standard in the factory coupes weren't designed for the type of wheeling and drivetrain we had in mind, we needed to look in a different direction.

While researching the lineage of the Viper power-plant we found the 48RE to be the only automatic transmission ever placed behind the mighty 8.3L V-10. Showing up in the SRT-10 Ram trucks, this beefy automatic was the obvious transmission for our needs. Though the 48RE behind the V-10 was only available with a two-wheel-drive tailhousing, the overall case and internals are basically the same as the 48RE in our '06 Dodge Ram 4x4 powered by the 5.9L Cummins diesel.

1. For the 48RE to communicate and shift properly behind the V-10 we needed an early version of the transmission to utilize the mechanically controlled kick-down cable. While a later-model electronically controlled unit may have worked, we are suckers for keeping things simple. On the engine side we simply swapped out the coupe throttle body for the SRT-10 truck unit since it is equipped with the appropriate cable guides and attachment points.

1. For the 48RE to communicate and shift properly behind the V-10 we needed an early versi

Remembering that the stock unit in our '06 Ram had a couple of weak points once we turned up the power, we looked to the transmission experts at North American Diesel Performance to build us a 48RE that could handle all the grunt of the Viper V-10. NADP builds transmissions to withstand the 1,000-plus horsepower and torque potential that the robust Cummins diesels are known to put out after performance modifications, so the 540 hp and 580 lb-ft of the 8.3L would hardly be a challenge for the company.

Still wrenching away in Wilmington, North Carolina, with the performance perfectionist at National Speed, we continued shoehorning the massive powertrain into our Rockwell-equipped Heavy Metal Mudder. Be sure to check back next month as we follow up our bulletproof transmission with a geardriven transfer case and start work on the V-10 fuel delivery system.

2. A block spacer and SRT-10 flexplate are required to mate the 48RE to the 8.3L engine. Since these two parts are not common junkyard finds we sourced ours from the Viper performance and parts Mecca that is Arrow Racing Engines.
2. A block spacer and SRT-10 flexplate are required to mate the 48RE to the 8.3L engine. S
3. Without question one of the trickest parts of our transmission is the custom torque converter from NADP. With the company's Heavy Hauler Triple Disc setup, NADP was able to design us a converter that provides incredible lock friction and fluid coupling. This equates to a converter that is strong, reliable, and ready to withstand all the power our Viper engine can throw at it.
3. Without question one of the trickest parts of our transmission is the custom torque con
4. NADP transmissions sit behind some of the most powerful diesels on the planet, so the pros there understand how important it is to build a transmission that can not only take power, but deliver it consistently. Billet internals, an upgraded valve body, and performance clutches are just a few of the high-performance improvements that make our 48RE Heavy Hauler transmission capable of withstanding demanding off-road conditions.
4. NADP transmissions sit behind some of the most powerful diesels on the planet, so the p

5. Before bolting the transmission in place we filled the converter with synthetic ATF from Mobil 1. While transmission fluid requirements differ amongst makes and models, synthetic is usually a safe bet because it is designed to keep fluid temperatures lower. This is important, as excessive heat is deadly to an automatic transmission.
5. Before bolting the transmission in place we filled the converter with synthetic ATF fro
6. To support the beefy 48RE we used a Mountain Off-Road Enterprises 13/4 bushing kit and had Momentum Performance build us a set of custom crossmember mounts to weld to the frame. TIG-welding each laser-cut mount, we opted to hard mount the transmission for increased ground clearance.
6. To support the beefy 48RE we used a Mountain Off-Road Enterprises 13/4 bushing kit and
7. In order for our new crossmember and drivetrain to fit, we needed to delete some of the factory cross bracing. Using a Hobart Air Force 400 plasma cutter, we burnt through the old metal with one pass of the torch.
7. In order for our new crossmember and drivetrain to fit, we needed to delete some of the

8. Using 13/4x0.120 wall DOM tubing, Momentum's Bobby Downes fabricated a set of custom crossmemebers to support both our transmission and transfer case. While the overall size of the 48RE wasn't much larger than the factory transmission, with the drivetrain now pushed back close to a foot, we got creative with our tubing bends to allow enough room to clear the front driveshaft and exhaust.
8. Using 13/4x0.120 wall DOM tubing, Momentum's Bobby Downes fabricated a set of custom cr
9. Though the bulk of the transmission install is complete, we will revisit the final assembly in a later issue. This will allow us time to plumb our transmission cooler lines out of the way and spend time wiring the J-Tec controller that will make the transmission and engine work in harmony.
9. Though the bulk of the transmission install is complete, we will revisit the final asse
10. With the headers and transmission in place, we tackled the foot control pedals. With the new dog box firewall taking up a fair amount of room, we to had to transfer both the brake and gas pedal back and over close to 4 inches. Luckily, I have a very gravity-enriched physique so the pedal move didn't really affect my driving comfort.
10. With the headers and transmission in place, we tackled the foot control pedals. With t

Next Month
With lots still to do on our Heavy Metal Mudder, next moth we will continue our drivertrain install and get this Mopar monster a new transfer case. Once we find the geardriven torque divider a new home, we'll get started fueling up with a custom fuel cell and delivery system.