If you’re new to diesel trucks, welcome to the chaos.
You’ll hear people talking about “2nd Gens,” “common rail,” “12-valves,” and wondering why someone just paid soooo much for a 25+ year-old truck...
Don’t worry — we’ve got you. This is Diesel Trucks for Dummies: Cummins Edition.
How the Cummins + Ram Partnership Started
The Cummins story begins in 1989, when Dodge (now Ram) partnered with Cummins to offer a diesel engine in their pickups.
Back then, diesel trucks weren’t about speed or luxury.
They were about one thing: Work.
The original 12-Valve, 5.9L Cummins turbo diesel quickly built a reputation for:
- Durability
- Simplicity
- Torque
- Efficiency (20+mpg is quite common)
Almost overnight, the Cummins-powered Ram became a legend.
How to Speak Cummins
Unlike Duramax trucks, which are referred to by RPO code (LBZ, LML, etc.), or Powerstrokes, which are referred to by engine displacement (7.3, 6.0, etc.), Cummins fans refer to their trucks by generation.
Here’s the quick breakdown:
- 1st Gen: (1989–1993) → The original square-body workhorse
- 2nd Gen: (1994–2002) → The iconic body style everyone loves
- 3rd Gen: (2003–2009) → More modern, introduces common rail
- 4th Gen (2010–2018) → Big jump in comfort and refinement
- 5th Gen (2019–present) → Modern, powerful, and more complex
So when someone says “I’ve got a 3rd Gen,” they’re saying they have a 2003-2009 Ram 2500/3500 with the 5.9 or 6.7 Cummins engine.
Why People Love Cummins Trucks
There’s a reason Cummins-powered Rams have such a loyal following. They’re built to make power, work, and hold up to extreme environments.
Power Potential
Every generation of Cummins engine is incredibly strong and responds well to modifications. Especially with the 6.7 Cummins that was introduced in 2007, it's very easy (not cheap) to make 1,000+ horsepower.
Towing Capability
Cummins-powered Rams are known for being some of the best trucks in the world when it comes to towing. That signature Cummins grunt is hard to beat.
Aftermarket Support
There are endless parts available for Cummins engines — from basic maintenance to full race builds.
They’re Relatively Simple
From the legendary 12-valve to the mighty 6.7, the Cummins is a relatively simple inline-6. There's just not a lot to go wrong with the engine itself.
The Engines (Quick and Simple)
You’ll also hear people refer to Cummins engines by type:
- 12-valve (1989–1998) → Mechanical, simple, legendary
- 24-valve (1998.5–2002) → More power, still relatively simple
- Common Rail 5.9 (2003-2007)* → Electronic fuel system, more power and tuning potential
- 6.7 Cummins (2007.5+) → More torque, modern emissions systems, tons of power potential
Each version has its own personality — and its own fanbase.
Let’s Talk About the Downsides
No truck is perfect. And Cummins-powered Rams definitely have their quirks.
Transmission Issues
This is the big one. For years, the engines made more torque than the transmissions could comfortably handle.
Common transmissions like the:
- 47RE
- 48RE
- 68RFE
Have all had their share of complaints — especially at higher power levels.
The aftermarket has largely solved this with built transmissions—but be prepared to spend $10,000 or more in many cases.
Interior Quality (Especially Older Trucks)
Let’s be honest—older Cummins trucks were not luxury vehicles.
1st, 2nd, and even 3rd Gen trucks were very much:
- Basic
- Functional
- Work-focused
Interior materials, ride quality, and refinement lagged behind competitors for years.
That changed significantly with the 4th Gen and newer trucks, which are much more comfortable and refined.
What Beginners Usually Don’t Know
If you’re new to Cummins trucks, here are a few things to keep in mind:
- The Cummins engine is great — it's typically the rest of the truck that will cause you headaches
- Buying an already modified/built truck can save you money on parts, but cost you a fortune on maintenance
- If shopping for a 1st, 2nd, or 3rd Gen, remember those trucks are decades old. Maintenance matters a LOT.
The Bottom Line
Cummins-powered Rams have earned their place as one of the most respected diesel platforms ever built.
They offer:
- Fantastic towing abilities
- Endless aftermarket support
- Unlimited build potential
- Strong resale value
But they also come with trade-offs like transmission limitations and (mostly in older trucks), less refinement. It’s all part of the package.
Have questions? We're here to help.
- Phone: 636-429-7020
-
Email: info@fassmotorsports.com
FASS Motorsports
25 Town and Country Drive
Washington, MO 63090
