1st Gen 5.9L 12V Cummins Specs, History, & Tow Capacity
1989-1993 Dodge D/W 250 & 350 with 5.9L Cummins 12V Diesel engine
If you’re familiar with diesel trucks, you’ve probably heard of the first generation Cummins. In my opinion, it’s by far the most reliable diesel engine ever put into a pickup truck, with the only close competition coming from the 7.3L Powerstroke. Even today, 30 years later after their inception, there are multitudes of 1st Gen 5.9L Cummins trucks on the road. When the 5.9L 12-Valve Cummins engine was introduced to Dodge’s D/W truck lineup, it created a new standard for OEM diesel performance. The 1st Gen 5.9L Cummins had unique specs never before seen on a diesel pickup truck, including a Holset fixed geometry turbocharger and direct fuel injection. These allowed Dodge’s D/W 250 and 350 to give truck owners a best-in-class 400 lb-ft of torque while also improving drivability and throttle response.
Although the 160 horsepower and 400 lb-ft of torque doesn’t seem impressive by today’s standards, they were very impressive for the time. Today, we know the first gen Cummins to be capable of producing high horsepower and torque numbers incredibly easily. High performance numbers can also be achieved cheaply, and the 6BT engine is more than capable of handling extra power without adding too many support modifications. We’ll go into more detail on increasing performance on our first gen 5.9L Performance upgrades post.

1st Gen 5.9L Cummins Reliability
There are a lot of contributing factors to the impressive reliability of the 5.9L Cummins. The engines were built to be robust, because they were initially created for commercial and agricultural applications. They also lacked modern emissions devices and complex electronics, both of which give greater opportunities for failure. Have you ever heard of the acronym, “KISS”? It stands for “keep it simple stupid”. That’s exactly what Cummins and Ram did. By using an inline-6 engine design, they had less problems because they had less parts. These engines also take up less space than a traditional V8, making it so easy to fix and work on these trucks.
Variations of the 5.9L Cummins are often used in race competitions or sled pulling events because of their ability to take a beating. Here are some of the key features that make these engines so durable.
- Gear-Driven Components
- Large Crankshaft & Forged Steel Connecting Rods
- 7 Main Bearings
- 6 Head Bolts per cylinder
- intercooler
- turbocharger
Key Performance Characteristics
The fuel injection and forced air induction systems play a major role in 5.9L Cummins performance. The 12v 5.9L Cummins was the first engine to deploy direct injection as its fuel injection strategy. It was also the first to offer a turbocharger and an intercooler.
5.9L Cummins Fuel Injection System
Unlike Ford or GM’s 8 cylinder diesel pickups during the same time period, the 12v Cummins used direct injection. Direct fuel injection results in greater efficiency by injecting fuel directly into the combustion chamber. There isn’t any pre-combustion event and it led to noticeable power gains over traditional indirect injection engines.

Forced Air Induction System
The 1st Gen Cummins was the first 3/4 ton and 1 ton diesel engine to use a turbocharger to increase performance. It was revolutionary for the time, and had a huge impact on drivability and towing capability. Turbochargers increase the amount of compressed air getting to the engine by using exiting exhaust gases. More condensed air means more power, fuel economy, and better towing performance, especially at higher altitudes.
An intercooler was added in 1991 to further enhance the air induction system. Intercoolers cool the compressed air from the turbocharger, creating denser air that enters the engine. Denser air results in a more efficient combustion process. That means greater fuel economy, lower EGTs, and more power. This feature makes the 91.5-93 model year trucks slightly more desirable than 89-91 trucks.
First Gen Cummins Transmissions
The 5.9L Cummins engine could be paired with either a manual or automatic transmission. The Getrag 5-speed manual transmission is the ideal partner to this Cummins engine. It holds up to extra horsepower the best, and with the addition of a performance clutch, it can help make some big numbers. The early automatic transmissions were clunky, and don’t hold up to the extra power as well. They’re also more expensive to fix and rebuild. The two automatic transmissions available on the 1st Gen Cummins are the A727 Torqueflite 3-Speed Automatic and the 4-speed A518, or 46RH, automatic transmission with overdrive. The 46RH is more desirable between the two automatic transmissions as it will allow for much better fuel economy.
Transmission Options 1989-1993 Dodge Diesel Trucks
Take a look below at the chart to see the available transmissions on 1989-1993 Diesel Ram trucks. I included a ranking system to show which transmission is most desirable. The standard transmission on Cummins diesel trucks is 5-speed Getrag 360 and it is also the most desirable.
Ranking | Type | Transmission |
1 | 5-Speed Manual Transmission /w Overdrive | Getrag 360 |
2 | 4-Speed Automatic Transmission /w Overdrive | A518 (46RH) |
3 | 3-Speed Automatic Transmission | A727 |
1st Gen 12 Valve 5.9L Cummins Specs
1st Gen 5.9L Cummins Years: | 1989-1993 |
Common Names: | 6BT Cummins 12V or 12 Valve Cummins 1st Generation Cummins |
Engine Design: | Inline-6 Cylinder |
Block: | Cast Iron |
Cylinder Head: | Cast Iron /w 6 Head Bolts per cylinder |
Displacement: | 5.9 Liters or 359 Cubic Inches |
Bore: | 4.02″ |
Stroke: | 4.72″ |
Compression Ratio: | 17.0:1 |
Firing Order: | 1-5-3-6-2-4 |
Fuel Injection: | Bosch VE44 Mechanical injection pump, mechanical injectors, direct-chamber fuel injection |
Turbocharger: | Holset Fixed Geometry Turbocharger (VGT) |
Valvetrain: | Overhead Valve Engine (OHV) 2 Valves Per Cylinder |
Pistons: | Cast Aluminum |
Transmissions | – Getrag 360 5-Speed Manual – Torqueflite A727 3-Speed Automatic – A518 (46RH) 4-Speed Automatic Transmission with overdrive |
Battery | Early Models – One 1,025 CCA Battery Later Models: Dual 750 CCA Batteries |
Weight: | 1,100 lbs dry |
Engine Oil Capacity /w Filter: | 12 Quarts or 11.4 Liters |
Fuel: | Diesel |
Governed Speed: | 2,500 RPM |
Horsepower | 160 horsepower @ 2,500 rpm |
Torque | 400 lb-ft @ 1700 rpm |
First Gen 5.9L Cummins History

Ford and GM already had diesel trucks available with vastly superior torque, towing, and fuel economy compared to Dodge’s gas-guzzling line-up. Sales were low, and Dodge needed an answer. In 1989, Dodge partnered with Cummins, incorporating a 5.9L 12-Valve Cummins engine into the D/W 250 and 350 trucks. The first generation Cummins engine single-handedly saved Dodge’s truck line-up, and gave them the ability to compete with Ford and GM.
This first engine supplied by Cummins is known by a couple of different names including the 6BT Cummins or 12-Valve Cummins. People familiar with the diesel industry refer to Dodge’s 1989-1993 D/W 250 and 350 lineup as the 1st generation Cummins. The engine was originally used in agriculture solutions which turned out to be a great thing for owners. These trucks are built incredibly solid, almost over-built for a 3/4 ton or 1 ton pickup truck.
The partnership between Dodge and Cummins was so successful that it still exists, with a new 6.7L Cummins engine used in Ram’s 5th Generation trucks today.
1st Gen 5.9L 12v Cummins Tow Capacity And Payload
1st Gen 5.9L 12v Cummins towing specs vary depending on cab and model configurations. Max tow capacity for a First Generation 5.9l Cummins is 11,900 lbs. Take a look at your owner’s manual for the exact towing and payload limitations of your vehicle.
Model | Trans. | Rear Axle Ratio | GVWR | Max Trailer weight |
D250 4×2 Reg Cab | Getrag Manual 46rh Auto /w Cooler | 3.07/3.54 4.10 3.54/4.10 3.54 | 8,510 lbs 8,510 lbs 8,510 lbs 8,510 lbs | 10,900 lbs 11,900 lbs 7,000 lbs 9,000 lbs |
D250 4×2 Club Cab | Getrag Manual 46rh Auto /w Cooler | 3.07/3.54 4.10 3.54/4.10 3.54 | 8,510 lbs 8,510 lbs 8,510 lbs 8,510 lbs | 10,600 lbs 11,600 lbs 6,700 lbs 8,700 lbs |
D350 4×2 Reg Cab SRW | Getrag Manual 46rh Auto /w Cooler | 3.54/4.10 3.54/4.10 3.54 | 8,700 lbs 8,700 lbs 8,700 lbs | 10,900/11,900 lbs 7,000 lbs 9,000 lbs |
D350 4×2 Reg Cab DRW | Getrag Manual 46rh Auto /w Cooler | 3.54/4.10 3.54/4.10 3.54 | 10,100 lbs 10,100 lbs 10,100 lbs | 10,700/11,700 lbs 6,800 lbs 8,800 lbs |
D350 4×2 Club Cab DRW | Getrag Manual 46rh Auto /w Cooler | 3.54 4.10 3.54/4.10 3.54 | 10,100 lbs 10,100 lbs 10,100 lbs 10,100 lbs | 10,400 lbs 11,400 lbs 6,500 lbs 8,500 lbs |
W250 4×4 Reg Cab | Getrag Manual 46rh Auto /w Cooler | 3.07/3.54 4.10 3.54/4.10 3.54 | 8,510 lbs 8,510 lbs 8,510 lbs 8,510 lbs | 10,400 lbs 11,400 lbs 6,500 lbs 8,500 lbs |
W250 4×4 Club Cab | Getrag Manual 46rh Auto /w Cooler | 3.07/3.54 4.10 3.54/4.10 3.54 | 8,510 lbs 8,510 lbs 8,510 lbs 8,510 lbs | 10,100 lbs 11,100 lbs 6,200 lbs 8,200 lbs |
W350 4×4 Reg Cab SRW | Getrag Manual 46rh Auto /w Cooler | 3.54/4.10 3.54/4.10 3.54 | 8,700 lbs 8,700 lbs 8,700 lbs | 10,400/11,400 lbs 6,500 lbs 8,500 lbs |
W350 4×4 Reg Cab DRW | Getrag Manual 46rh Auto /w Cooler | 3.54/4.10 3.54/4.10 3.54 | 10,100 lbs 10,100 lbs 10,100 lbs | 10,200/11,200 lbs 6,300 lbs 8,300 lbs |
W350 4×4 Club Cab DRW | Getrag Manual 46rh Auto /w Cooler | 3.54/4.10 3.54/4.10 3.54 | 10,100 lbs 10,100 lbs 10,100 lbs | 9,900/10,900 lbs 6,100 lbs 8,100 lbs |
First Gen 5.9L Cummins Cab Specs
You’ll find a list of 1st gen 5.9L Cummins cab specs below. These cab specifications are based off of the 1993 model year Ram D/W 250 and 350 trucks. Crew cabs weren’t available on these models. The two cab configurations were regular cabs and club cabs. The Club cab truck is the equivalent of today’s extended cab. They had long and short bed configurations available with both regular cabs and club cabs.
1993 Dodge Ram Truck
Model: | wheelbase | Total Length | Box Length | Box width | Box depth | Tailgate Opening |
Reg. Cab Short bed | 115″ | 193.8″ | 76.9″ | 70.0″ | 19.1″ | 67.36″ |
Reg. Cab Long Bed | 131″ | 213.8″ | 96.9″ | 70.0″ | 19.1″ | 67.36″ |
club cab short bed | 133″ | 211.8″ | 76.9″ | 70.0″ | 19.1″ | 67.36″ |
club cab long bed | 149″ | 231.8″ | 96.9″ | 70.0″ | 19.1″ | 67.36″ |
Interior Specs
1993 Dodge Ram Truck
Head Room | 40″ |
Shoulder Room | 64.2″ |
Hip Room | 65″ |
Leg Room | 39.4″ |
Other First Gen Cummins Resources
Learn more 1st Gen 5.9L Cummins specs and information in the resources below. Click on the links to go to that page.
- 1st Generation Cummins Maintenance Guide & Parts List
- Best 1st Gen Cummins Performance Upgrades