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2021 RAM 2500 Diesel Trucks for Sale Under $45K (2025 Buyer’s Guide) GuideMechanic.Com The 2021 RAM 2500 diesel truck continues to be one of the top choices for drivers who need serious towing power, modern comfort, and long-term durability.
Whether you’re a contractor, farmer, RV hauler, or diesel enthusiast, the 2021 RAM 2500 with the 6.7L Cummins turbo diesel delivers everything you expect in a heavy-duty pickup.
And the good news? As of 2025, many well-maintained 2021 RAM 2500 diesel trucks are now available for under $45,000.
See Also: 2019 Chevy Silverado 4×4 Trucks for Sale Under $35K
2021 RAM 2500 Diesel Trucks for Sale Under $45K (2025 Buyer’s Guide)
In this guide, we’ll cover:
- Why the 2021 RAM 2500 Diesel is a smart buy
- What to expect at the $45K price point
- A detailed price table of current listings
- Key things to look for when buying used
- Where to find the best deals in 2025
Why Choose the 2021 RAM 2500 Diesel?
The 2021 model year continued RAM’s tradition of powerful performance combined with advanced technology and upscale interiors. Key benefits include:
6.7L Cummins Turbo Diesel Engine
- 370 hp and 850 lb-ft of torque
- Excellent towing capacity: up to 19,680 lbs when properly equipped
- Proven long-term durability and strong aftermarket support
Strong Towing & Payload Capabilities
- Available with fifth-wheel/gooseneck prep package
- Integrated trailer brake controller
- Optional rear air suspension for better load leveling
Comfortable & Functional Interior
- Available trims range from basic work-ready Tradesman to luxurious Laramie
- Apple CarPlay, Android Auto, Uconnect touchscreen
- Crew Cab models offer excellent passenger space
Advanced Safety Features
- Available blind spot monitoring, adaptive cruise control, and forward collision warning
2021 RAM 2500 Diesel Trucks Under $45K: Pricing Table (2025)
Here’s a sample of real-world pricing based on current listings from dealers and online platforms in 2025:
| Trim | Engine | Mileage | Cab/Bed | Drivetrain | Estimated Price | Notable Features |
|---|---|---|---|---|---|---|
| Tradesman | 6.7L Cummins Diesel | 90,000 miles | Crew Cab / 6.4 ft | 4×4 | $41,900 | Vinyl seats, trailer tow pkg |
| Big Horn | 6.7L Cummins Diesel | 100,000 miles | Crew Cab / 6.4 ft | 4×4 | $43,500 | Chrome pkg, Apple CarPlay |
| Tradesman | 6.7L Cummins Diesel | 85,000 miles | Regular Cab / 8 ft | 4×2 | $40,200 | Long bed, gooseneck ready |
| Big Horn Night | 6.7L Cummins Diesel | 110,000 miles | Crew Cab / 6.4 ft | 4×4 | $44,800 | Blackout package, tow mirrors |
| SLT | 6.7L Cummins Diesel | 95,000 miles | Crew Cab / 6.4 ft | 4×4 | $44,900 | Power driver seat, cloth interior |
| Tradesman | 6.7L Cummins Diesel | 105,000 miles | Crew Cab / 8 ft | 4×4 | $42,300 | Utility bed, trailer brake, clean history |
Prices reflect mid-2025 market values and may vary based on location, truck condition, and dealer inventory.
What to Expect at the Under $45K Price Point
When shopping under $45,000, most 2021 RAM 2500 diesel trucks will have 80,000 to 120,000 miles, but that’s considered mid-life for a Cummins diesel engine, which often exceeds 300,000 miles with proper care.
You’ll likely find:
- Mostly Tradesman and Big Horn trims
- Crew Cab and Regular Cab models
- Mostly 4×4 with some 4×2 long bed options
- Functional interiors, fewer luxury upgrades
2021 RAM 2500 Diesel Trucks for Sale Under $45K (2025 Buyer’s Guide)
What to Look for When Buying Used
Buying a used heavy-duty diesel truck requires careful inspection. Here are the top things to check before buying a 2021 RAM 2500 diesel:
1. Maintenance History
Look for:
- Regular oil changes (every 7,500 miles or less)
- Fuel filter replacement
- Transmission service (especially for 68RFE auto)
- DEF system and emissions maintenance
2. Transmission Type
- The 2021 RAM 2500 offers:
- 6-speed 68RFE automatic (standard)
- 6-speed Aisin AS69RC (in 3500 or specific HO trims only)
Make sure the transmission shifts smoothly and doesn’t slip or hesitate. A transmission service record is a big plus.
3. 4×4 System Functionality
- Engage both 4WD High and Low
- Listen for unusual noises during operation
- Check U-joints and transfer case for leaks
4. Emissions Equipment Health
- Ask about DPF (diesel particulate filter) and EGR servicing
- Trucks used only for short drives may have more DPF issues
- Look for dashboard warning lights related to emissions
2021 RAM 2500 Diesel Trucks for Sale Under $45K (2025 Buyer’s Guide)
Best Trims for Value Under $45K
| Trim | Why It’s a Smart Buy |
|---|---|
| Tradesman | Budget-friendly work truck with reliable diesel power |
| Big Horn | Great balance of features, comfort, and utility |
| SLT | Slightly more upscale with improved interior materials |
| Night Edition | Looks sharp with blackout styling; may include better wheels & tires |
Where to Find 2021 RAM 2500 Diesel Trucks for Sale Under $45K
Online Marketplaces
- CarGurus, AutoTrader, Cars.com: Use advanced filters: 2021, diesel, under $45K, 4×4
- Facebook Marketplace and Craigslist: Good for local deals and private sellers
Dealerships & Fleet Resellers
- RAM dealers with off-lease trucks
- Utility companies or construction fleets upgrading inventory
- Often maintained better than individual seller vehicles
Auctions & Government Surplus
- GovDeals and Municibid sometimes list work trucks with lower prices
- Trucks from municipal fleets are typically well-serviced
Why the 2021 Model Year Is a Smart Choice
Compared to newer RAM 2500 models, the 2021 strikes an excellent balance between modern features and affordability:
| Feature | Benefit |
|---|---|
| Latest Cummins diesel tech | Lower emissions, strong torque, proven reliability |
| Updated interior design | More modern feel vs pre-2019 models |
| Still depreciating | Can find solid deals under $45K |
| Easier to finance | Lower monthly payments than 2022–2023 models |
Common Upgrades and Add-Ons
Many trucks under $45K may already include popular upgrades such as:
- Fifth-wheel/gooseneck hitches
- Running boards / step bars
- Off-road tires or wheels
- Spray-in bedliners
- Tonneau covers
These add extra value and can save you from spending more on accessories later.
Final Thoughts: Power and Practicality for Less Than $45K
The 2021 RAM 2500 Diesel is a serious workhorse with a reputation for long-lasting performance and top-tier towing.
For under $45,000, you can get a well-equipped truck with a Cummins engine, solid 4×4 capability, and modern features—all without breaking the bank.
Whether you’re towing a trailer, hauling heavy loads, or just want a reliable diesel pickup with room for the crew, this truck checks all the boxes.
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