SUPER RARE DIESEL FIND â" 2021 GMC Sierra 2500 AT4 â" Only 54,253 Miles! This is not your average heavy-duty truck â" this is the 2021 GMC Sierra 2500 AT4 Diesel, fully loaded and ready to dominate both the worksite and weekend adventures. Under the hood? A legendary 6.6L Duramax Turbo-Diesel V8 paired with a 10-speed Allison transmission, delivering incredible torque and towing power. With a GVWR of 11,350 lbs, this truck is built to haul, tow, and take on anything you throw at it. But power is just the beginning â" this AT4 is loaded with luxury and cutting-edge tech, featuring:
Technology Package â" Heads-Up Display, Rear Camera Mirror, HD Surround Vision.
Driver Alert Package I & II â" Lane Departure Warning, Rear Cross Traffic Alert, Forward Collision Alert, and more. Premium Plus Package â" Ultimate comfort and premium interior finishes. Preferred Package â" Convenience features that make every ride smoother. X31 Off-Road Package â" Off-road tuned suspension, skid plates, and hill descent control. Power Running Boards â" Sleek, automatic access with a bold look, And SO much more!
This diesel-powered beast is in excellent condition â" a rare find in the pre-owned market. Trucks like this donât last long, especially when theyâre this clean, this capable, and this well-equipped.
Why Buy from OâNeil Nissan in Warminster, PA?
â"ï¸ No Hidden Fees â" Ever
â"ï¸ Top Dollar for Your Trade
â"ï¸ Clear, Upfront Pricing â" No Surprises
â"ï¸ 5-Star Customer Experience â" Start to Finish
Whether you're chasing trails, towing heavy, or just want to ride in rugged luxury â" this 2021 Sierra 2500 AT4 Diesel is the truck that checks every box.
ð' Donât miss your chance â" schedule a test drive today at OâNeil Nissan before it's gone!
Used 2021 GMCSierra 2500 HD AT4
- Exterior Color
- Onyx Black
- Interior Color
- Jet Black
- Odometer
- 54,253 miles
- Body/Seating
- Truck Crew Cab/5 seats
- Transmission
- 10-Speed Automatic
- Drivetrain
- 4x4
- Engine
- V-8 cyl
- VIN
- 1GT49PEY6MF263448
- Stock Number
- 7567
Highlighted Features
- Leather upholstery
- Automatic temperature control
- Premium audio system
- Wireless phone connectivity
- Front dual zone A/C
- Auto-dimming rearview mirror
- Split folding rear seat
- Memory seat
- Heated front seats
- Ventilated front seats
- Perimeter/approach lights
- Remote keyless entry
Included Packages & Accessories
- Navigation System
- 6 Speakers
- AM/FM radio: SiriusXM with 360L
- Premium audio system: Premium GMC Infotainment System
- Steering Wheel Audio Controls
- Air Conditioning
- Automatic temperature control
- Electric Rear-Window Defogger
- Front dual zone A/C
- Rear window defroster
- 12-Volt Rear Auxiliary Power Outlet
- 120-Volt Bed Mounted Power Outlet
- 120-Volt Instrument Panel Power Outlet
- Memory seat
- Power driver seat
- Power steering
- Power windows
- Power Windows w/Driver Express Up/Down
- Remote keyless entry
- Remote Vehicle Starter System
- Steering wheel mounted audio controls
- Manual Tilt-Wheel/Telescoping Steering Column
- Speed-sensing steering
- Traction control
- 4-Wheel Disc Brakes
- ABS brakes
- Dual front impact airbags
- Dual front side impact airbags
- Electrical Lock Control Steering Column
- Front anti-roll bar
- Front wheel independent suspension
- Keyless Open & Start
- Low tire pressure warning
- Occupant sensing airbag
- Overhead airbag
- Power Door Locks
- Pickup Box
- Brake assist
- Electronic Stability Control
- Lane Departure Warning System
- Delay-off headlights
- Front fog lights
- Fully automatic headlights
- Panic alarm
- Security system
- Unauthorized Entry Theft-Deterrent System
- Speed control
- 2-Speed Active Transfer Case
- 220 Amps Alternator
- Heavy-Duty 80 Amp Battery
- High Idle Switch
- AT4 High Clearance Step (LPO)
- Auto-dimming door mirrors
- Bumpers: body-color
- GMC MultiPro Tailgate Step Lights (LPO)
- Heated door mirrors
- LED Cargo Area Lighting
- Painted Black Surround Grille
- Power door mirrors
- Power-Retractable Black Assist Steps
- Rear step bumper
- Rear Wheelhouse Liners
- Red Recovery Hooks
- Spray-On Pickup Box Bed Liner w/AT4 Logo
- Turn signal indicator mirrors
- 2 USB Ports
- 2 USB Ports (1st Row)
- 2nd Row Dual USB Charge-Only Ports
- 4.2" Diagonal Color Display Driver Info Center
- Apple CarPlay/Android Auto
- Auto-dimming Rear-View mirror
- Compass
- Compass Located In Instrument Cluster
- Driver door bin
- Driver vanity mirror
- Floor-Mounted Center Console
- Front Prem Floor Liners w/Removable Carpet Insert
- Front reading lights
- HD Rear Vision Camera
- Heated steering wheel
- Illuminated entry
- Outside temperature display
- Overhead console
- Passenger vanity mirror
- Rear Prem Floor Liners w/Removable Carpet Insert
- Rear reading lights
- Rear seat center armrest
- Tachometer
- Telescoping steering wheel
- Tilt steering wheel
- Trip computer
- Voltmeter
- Wireless Phone Projection
- Front Center Armrest
- Heated & Ventilated Front Bucket Seats
- Heated 2nd Row Outboard Seats
- Heated Driver & Front Outboard Passenger Seats
- Heated front seats
- Heated rear seats
- Perforated Leather-Appointed Front Seat Trim
- Power passenger seat
- Split folding rear seat
- Ventilated front seats
- Passenger door bin
- Hitch Guidance w/Hitch View
- In-Vehicle Trailering System App
- Integrated Trailer Brake Controller
- 18" Machined Aluminum Wheels
- 20" Machined Aluminum Wheels
- Alloy wheels
- Wheels: 20" Aluminum High Gloss Black (LPO)
- Wheels: 20" Transit Aluminum
- Deep-Tinted Glass
- Power Front Passenger Windows w/Express Up/Down
- Power Rear Windows w/Express Down
- Variably intermittent wipers
- 3.42 Axle Ratio
- O'Neil Nissan is the Most Awarded Dealer in PA
- 3-Time Global Award 21-22-23
- 7-Time Owners First Award of Excellence
- Family Owned and Operated for almost 40 years
- Check Out Our Reviews
- AT4 Preferred Package
- AT4 Premium Plus Package
- Driver Alert Package I
- Driver Alert Package II
- Technology Package
- X31 Off-Road Package
- 6-Speaker Audio System Feature
- Bose Premium 7 Speaker Sound System
- HD Radio
- Radio: AM/FM w/Premium GMC Infotainment System
- Radio: Premium GMC Infotainment Sys w/Navigation
- SiriusXM w/360L
- Driver Memory
- Universal Home Remote
- Off-Road Suspension
- Power Sunroof
- Hill Descent Control
- Perimeter Lighting
- IntelliBeam Automatic High Beam On/Off
- 4G LTE Wi-Fi Hotspot Capable
- 8" Multicolor Driver Information Center
- Automatic Emergency Braking
- Following Distance Indicator
- Forward Collision Alert
- GMC Connected Access Capable
- HD Surround Vision
- Inside Rearview Auto-Dimming Rear Camera Mirror
- Lane Change Alert w/Side Blind Zone Alert
- Multicolor 15" Diagonal Head-Up Display
- OnStar & GMC Connected Services Capable
- Rear Cross Traffic Alert
- Ultrasonic Front & Rear Park Assist
- Wireless Charging
- 10-Way Power Driver Seat Adjuster w/Lumbar
- 10-Way Power Passenger Seat Adjuster w/Lumbar
- Front Bucket Seats
- Safety Alert Seat
- Power Sliding Rear Window w/Defogger
Detailed Specifications
- 1-touch down
- 1-touch up
- Air conditioning
- Auto-dimming rearview mirror
- Automatic temperature control
- Driver door bin
- Driver vanity mirror
- Front beverage holders
- Front dual zone A/C
- Heated steering wheel
- Illuminated entry
- Memory seat
- Overhead console
- Passenger door bin
- Passenger vanity mirror
- Power windows
- Proximity key: doors and push button start
- Rear beverage holders
- Rear door bins
- Remote engine start: keyfob
- Remote keyless entry
- Speed control
- Telescoping steering wheel
- Tilt steering wheel
- Alloy wheels
- Front anti-roll bar
- Front wheel independent suspension
- Power steering
- Single rear wheels
- Speed-sensing steering
- Tires: all-terrain
- 1st row LCD monitors: 2
- AM/FM radio: SiriusXM with 360L
- Premium audio system: Premium GMC Infotainment System
- Primary LCD size: 8.0"
- Smart device integration: Android Auto/Apple CarPlay
- Steering wheel mounted audio controls
- Wireless phone connectivity: Bluetooth
- Front center armrest
- Front seats: bucket
- Heated front seats
- Heated rear seats
- Leather upholstery
- Max seating capacity: 5
- Power 2-way driver lumbar support
- Power 2-way passenger lumbar support
- Power driver seat
- Power passenger seat
- Rear seat center armrest
- Rear seats: split-bench
- Rear seats Folding position: fold-up cushion
- Seat Upholstery: leather
- Split folding rear seat
- Ventilated front seats
- Cylinder configuration: V-8
- Drive type: four-wheel
- Engine liters: 6.6L
- Engine location: front
- Fuel tank capacity: 36.0gal.
- Hybrid traction battery type: none
- Manual-shift auto
- Mode select transmission
- Rear locking differential
- Standard fuel economy fuel type: gasoline
- Variable valve control
- Ground clearance (min): 257mm (10.1")
- Auto-dimming door mirrors
- Bedliner
- Bumpers: body-color
- Heated door mirrors
- Left rear passenger door: conventional
- Power door mirrors
- Rear cargo: tailgate
- Rear step bumper
- Right rear passenger: conventional
- Skid plates
- Trailer hitch receiver
- Trailer sway control
- Turn signal indicator mirrors
- Exterior body width: 2,079mm (81.8")
- Exterior height: 2,023mm (79.7")
- Exterior length: 6,352mm (250.1")
- Front headroom: 1,093mm (43.0")
- Front hiproom: 1,554mm (61.2")
- Front legroom: 1,131mm (44.5")
- Front shoulder room: 1,677mm (66.0")
- Rear headroom: 1,013mm (39.9")
- Rear hiproom: 1,530mm (60.2")
- Rear legroom: 1,102mm (43.4")
- Rear shoulder room: 1,659mm (65.3")
- Turning radius: 8.0m (26.3')
- Wheelbase: 4,037mm (158.9")
- Appearance: analog
- Compass
- Delay-off headlights
- Front fog lights
- Front reading lights
- Fully automatic headlights
- Low tire pressure warning
- Oil pressure gauge
- Outside temperature display
- Rear reading lights
- Rear window defroster
- Tachometer
- Trip computer
- Variably intermittent wipers
- Voltmeter
- 4 wheel disc brakes
- ABS brakes
- Brake assist
- Dual front impact airbags
- Dual front side impact airbags
- Electronic stability
- Ignition disable
- Occupant sensing airbag
- Overhead airbag
- Panic alarm
- Perimeter/approach lights
- Security system
- Traction control
Standard Features
- AT4 Preferred Package
- Driver Alert Package I
- Driver Alert Package II
- Power Sunroof
- Technology Package
- HD Surround Vision
- Universal Home Remote
- Power Sliding Rear Window w/Defogger
- Radio: Premium GMC Infotainment Sys w/Navigation
- Bose Premium 7 Speaker Sound System
- Wireless Charging
- Inside Rearview Auto-Dimming Rear Camera Mirror
- Multicolor 15" Diagonal Head-Up Display
- 8" Multicolor Driver Information Center
- Ultrasonic Front & Rear Park Assist
- Lane Change Alert w/Side Blind Zone Alert
- Rear Cross Traffic Alert
- Perimeter Lighting
- Forward Collision Alert
- Automatic Emergency Braking
- IntelliBeam Automatic High Beam On/Off
- Following Distance Indicator
- Safety Alert Seat
- 6-Speaker Audio System Feature
- SiriusXM w/360L
- HD Radio
- 4G LTE Wi-Fi Hotspot Capable
- GMC Connected Access Capable
- 10-Way Power Driver Seat Adjuster w/Lumbar
- 10-Way Power Passenger Seat Adjuster w/Lumbar
- Driver Memory
- Off-Road Suspension
- Hill Descent Control
Dealer Notes
KBB.com Consumer Reviews
- 2.0
Transmission trash
By Jason on Monday, April 07, 2025
Bought a 2023 GMC Duramax diesel Sierra SLT had it for two years hit 50,000 miles. The throttlebody broke went in for service. Got it back three weeks at 62,000 miles now my transmission is slipping. I travel back-and-forth from South Carolina to North Carolina for work daughter’s truck would be my forever truck. What a joke Hundred thousand dollar truck junk - 5.0
Fantastic truck
By Jjj on Sunday, November 07, 2021
This one of the most solid vehicles that I have ever driven! The 401 hp engine is more than enough power and the transmission is smooth! Highly recommend this truck! - 3.0
Don't judge a truck by the appearance
By jmil on Wednesday, May 11, 2022
Great truck, loved it until the DEF tank heater malfunctioned and shut down the truck. Now sitting waiting for the replacement tank for over 10 weeks. Turns out every HD truck 2020 and 2021 has the same problem and all will need this replacement that is being produced at a snail's pace by GM. Per the dealership, last count, over 9000 trucks like mine are idle waiting for this part. $65000 waste of money and terrible service by GMC (not the local dealership).