2004.5-2005 GM 2500HD/3500HD 6.6L LL Duramax Engine & Performance

2004.5-2005 6.6L Silverado & Sierra 2500HD/3500HD

2004.5-2005 GM 2500HD/3500HD 6.6L LLY Duramax Crate Engines

Crate Engines

2004.5-2005 GM 2500HD/3500HD 6.6L LLY Duramax Gaskets, Gasket Kits & Bearings

Gaskets

2004.5-2005 GM 2500HD/3500HD 6.6L LLY Duramax Glow Plugs

Glow Plugs

2004.5-2005 GM 2500HD/3500HD 6.6L LLY Duramax Head Studs & Main Studs

Head Studs & Main Studs

2004.5-2005 GM 2500HD/3500HD 6.6L LLY Duramax Heads & Valve Train

Heads & Valve Train

2004.5-2005 GM 2500HD/3500HD 6.6L LLY Duramax Motor Mounts

Motor Mounts

2004.5-2005 GM 2500HD/3500HD 6.6L LLY Duramax Oil Pans

Oil Pans

2004.5-2005 GM 2500HD/3500HD 6.6L LLY Duramax Radiators & Cooling Upgrades

Radiators & Cooling Upgrades

2004.5-2005 GM 2500HD/3500HD 6.6L LLY Duramax Rebuild Kits & Internal Parts

Rebuild Kits & Internal Parts

2004.5-2005 GM 2500HD/3500HD 6.6L LLY Duramax Rods, Pistons, Cams & More

Rods/Pistons/Cams & More

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Cometic C15376-053 .053 inch MLX Cylinder Head Gasket - 4.130 inch Bore | 2001-2016 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
Cometic C15376-053 .053 inch MLX Cylinder Head Gasket - 4.130 inch Bore | 2001-2016 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

Cometic

Cometic C15376-053 .053 inch MLX Cylinder Head Gasket - 4.130 inch Bore | 2001-2016 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

SKU: COMC15376-053
$195.30
Cometic C15043 17-Bolt Fiber Oil Pan Gasket Lower - .060 inch | 2001-2016 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
Cometic C15043 17-Bolt Fiber Oil Pan Gasket Lower - .060 inch | 2001-2016 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

Cometic

Cometic C15043 17-Bolt Fiber Oil Pan Gasket Lower - .060 inch | 2001-2016 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

SKU: COMC15043
$19.03
BD Diesel 1081160 Turbo Cool Down Timer Kit v2.0 | 1994-1995 Ram 2500/3500 & 94-18 Ford Powerstroke & 01-14 GM 6.6L Duramax
BD Diesel 1081160 Turbo Cool Down Timer Kit v2.0 | 1994-1995 Ram 2500/3500 & 94-18 Ford Powerstroke & 01-14 GM 6.6L Duramax

BD Diesel

BD Diesel 1081160 Turbo Cool Down Timer Kit v2.0 | 1994-1995 Ram 2500/3500 & 94-18 Ford Powerstroke & 01-14 GM 6.6L Duramax

SKU: BDD1081160
$244.95
ARP 900-1150 4.115 Bore Ring Compressor | 2001-2016 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
ARP 900-1150 4.115 Bore Ring Compressor | 2001-2016 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

ARP

ARP 900-1150 4.115 Bore Ring Compressor | 2001-2016 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

SKU: ARP900-1150
$97.13
ARP 900-0950 4.095 Bore Ring Compressor | 2001-2016 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
ARP 900-0950 4.095 Bore Ring Compressor | 2001-2016 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

ARP

ARP 900-0950 4.095 Bore Ring Compressor | 2001-2016 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

SKU: ARP900-0950
$97.13
ARP 900-0400 4.040 Tapered Ring Compressor | 1989-2007 Dodge RAM 2500/3500 5.9L Cummins
ARP 900-0400 4.040 Tapered Ring Compressor | 1989-2007 Dodge RAM 2500/3500 5.9L Cummins

ARP

ARP 900-0400 4.040 Tapered Ring Compressor | 1989-2007 Dodge RAM 2500/3500 5.9L Cummins

SKU: ARP900-0400
$97.13
ARP 400-7534 Hex Head Valve Cover Bolt Kit | 2004.5-2016 GM 2500HD/3500HD 6.6L Duramax
ARP 400-7534 Hex Head Valve Cover Bolt Kit | 2004.5-2016 GM 2500HD/3500HD 6.6L Duramax

ARP

ARP 400-7534 Hex Head Valve Cover Bolt Kit | 2004.5-2016 GM 2500HD/3500HD 6.6L Duramax

SKU: ARP400-7534
$146.32
ARP 400-7532 Hex Head Valve Cover Bolt Kit | 2001-2004 GM 2500HD/3500HD 6.6L Duramax LB7
ARP 400-7532 Hex Head Valve Cover Bolt Kit | 2001-2004 GM 2500HD/3500HD 6.6L Duramax LB7

ARP

ARP 400-7532 Hex Head Valve Cover Bolt Kit | 2001-2004 GM 2500HD/3500HD 6.6L Duramax LB7

SKU: ARP400-7532
$108.39
aFe 77-44001 Power Scorcher Tuning Module | 2001-2011 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
aFe 77-44001 Power Scorcher Tuning Module | 2001-2011 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
aFe 77-44001 Power Scorcher Tuning Module | 2001-2011 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
aFe 77-44001 Power Scorcher Tuning Module | 2001-2011 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
aFe 77-44001 Power Scorcher Tuning Module | 2001-2011 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

AFE Power

aFe 77-44001 Power Scorcher Tuning Module | 2001-2011 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

SKU: AFE77-44001
$473.75
aFe 77-44002 Power Scorcher HD Tuning Module | 1999-2011 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
aFe 77-44002 Power Scorcher HD Tuning Module | 1999-2011 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
aFe 77-44002 Power Scorcher HD Tuning Module | 1999-2011 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
aFe 77-44002 Power Scorcher HD Tuning Module | 1999-2011 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
aFe 77-44002 Power Scorcher HD Tuning Module | 1999-2011 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

AFE Power

aFe 77-44002 Power Scorcher HD Tuning Module | 1999-2011 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

SKU: AFE77-44002
$473.75
SCT 7416 X4 Power Flash Programmer | 1999-2016 Applications
SCT 7416 X4 Power Flash Programmer | 1999-2016 Applications
SCT 7416 X4 Power Flash Programmer | 1999-2016 Applications
SCT 7416 X4 Power Flash Programmer | 1999-2016 Applications

SCT Performance

SCT 7416 X4 Power Flash Programmer | 1999-2016 Applications

SKU: SCT7416
$339.15
$399
Wehrli 100415 Billet Upper Valve Cover Set | 2004.5-2010 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
Wehrli 100415 Billet Upper Valve Cover Set | 2004.5-2010 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
Wehrli 100415 Billet Upper Valve Cover Set | 2004.5-2010 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
Wehrli 100415 Billet Upper Valve Cover Set | 2004.5-2010 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

Wehrli Custom Fab

Wehrli 100415 Billet Upper Valve Cover Set | 2004.5-2010 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

SKU: WCF100415-GB
From $435.53
Wehrli 100645 OEM Placement Coolant Tank Kit | 2001-2007 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
Wehrli 100645 OEM Placement Coolant Tank Kit | 2001-2007 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
Wehrli 100645 OEM Placement Coolant Tank Kit | 2001-2007 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
Wehrli 100645 OEM Placement Coolant Tank Kit | 2001-2007 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
Wehrli 100645 OEM Placement Coolant Tank Kit | 2001-2007 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

Wehrli Custom Fab

Wehrli 100645 OEM Placement Coolant Tank Kit | 2001-2007 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

SKU: WCF100645-GB
From $458.81
Gator Fasteners MSK667Y Main Stud Kit | 2001-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
Gator Fasteners MSK667Y Main Stud Kit | 2001-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
Gator Fasteners MSK667Y Main Stud Kit | 2001-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
Gator Fasteners MSK667Y Main Stud Kit | 2001-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
Gator Fasteners MSK667Y Main Stud Kit | 2001-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

Gator Fasteners

Gator Fasteners MSK667Y Main Stud Kit | 2001-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

SKU: GTFMSK667Y
$279.99
Sinister SD-WWP-01 Welded Water Pump | 2001-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax LB7 / LLY
Sinister SD-WWP-01 Welded Water Pump | 2001-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax LB7 / LLY
Sinister SD-WWP-01 Welded Water Pump | 2001-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax LB7 / LLY
Sinister SD-WWP-01 Welded Water Pump | 2001-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax LB7 / LLY
Sinister SD-WWP-01 Welded Water Pump | 2001-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax LB7 / LLY

Sinister Diesel

Sinister SD-WWP-01 Welded Water Pump | 2001-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax LB7 / LLY

SKU: SINSDWWP01
$265.99
Wehrli 100860 Upper Coolant Pipe Kit | 2001-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
Wehrli 100860 Upper Coolant Pipe Kit | 2001-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
Wehrli 100860 Upper Coolant Pipe Kit | 2001-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
Wehrli 100860 Upper Coolant Pipe Kit | 2001-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

Wehrli Custom Fab

Wehrli 100860 Upper Coolant Pipe Kit | 2001-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

SKU: WCF100860-GB
From $138.71
Wehrli 100405 Top Outlet Billet Thermostat Housing and Upper Coolant Pipe Kit | 2001-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
Wehrli 100405 Top Outlet Billet Thermostat Housing and Upper Coolant Pipe Kit | 2001-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
Wehrli 100405 Top Outlet Billet Thermostat Housing and Upper Coolant Pipe Kit | 2001-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
Wehrli 100405 Top Outlet Billet Thermostat Housing and Upper Coolant Pipe Kit | 2001-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
Wehrli 100405 Top Outlet Billet Thermostat Housing and Upper Coolant Pipe Kit | 2001-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

Wehrli Custom Fab

Wehrli 100405 Top Outlet Billet Thermostat Housing and Upper Coolant Pipe Kit | 2001-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

SKU: WCF100405
$445.23
PPE 118034000 Main Stud Kit | 2001-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
PPE 118034000 Main Stud Kit | 2001-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
PPE 118034000 Main Stud Kit | 2001-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
PPE 118034000 Main Stud Kit | 2001-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

PPE

PPE 118034000 Main Stud Kit | 2001-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

SKU: PPE118034000
$229.49
Choate Engineering CEP66LLYLD 6.6L Duramax Daily Driver Long Block | 2004.5-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax LLY
Choate Engineering CEP66LLYLD 6.6L Duramax Daily Driver Long Block | 2004.5-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax LLY

Choate Engineering

Choate Engineering CEP66LLYLD 6.6L Duramax Daily Driver Long Block | 2004.5-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax LLY

SKU: CHTCEP66LLYLD
$12,500
Choate Engineering CEP66LLYSW 6.6L Duramax Workhorse Short Block | 2004.5-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax LLY
Choate Engineering CEP66LLYSW 6.6L Duramax Workhorse Short Block | 2004.5-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax LLY

Choate Engineering

Choate Engineering CEP66LLYSW 6.6L Duramax Workhorse Short Block | 2004.5-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax LLY

SKU: CHTCEP66LLYSW
$11,100
Choate Engineering CEP66LLYLW 6.6L Duramax Workhorse Long Block | 2004.5-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax LLY
Choate Engineering CEP66LLYLW 6.6L Duramax Workhorse Long Block | 2004.5-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax LLY

Choate Engineering

Choate Engineering CEP66LLYLW 6.6L Duramax Workhorse Long Block | 2004.5-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax LLY

SKU: CHTCEP66LLYLW
$14,800
$15,400
Choate Engineering CEP66LLYSD Short Block Daily Driver Crate Engine | 2004.5-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax LLY
Choate Engineering CEP66LLYSD Short Block Daily Driver Crate Engine | 2004.5-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax LLY

Choate Engineering

Choate Engineering CEP66LLYSD Short Block Daily Driver Crate Engine | 2004.5-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax LLY

SKU: CHTCEP66LLYSD
$9,000
Sinister SD66EGRC045BLU EGR Cooler in Blue Finish | 2004.5-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax LLY
Sinister SD66EGRC045BLU EGR Cooler in Blue Finish | 2004.5-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax LLY
Sinister SD66EGRC045BLU EGR Cooler in Blue Finish | 2004.5-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax LLY
Sinister SD66EGRC045BLU EGR Cooler in Blue Finish | 2004.5-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax LLY
Sinister SD66EGRC045BLU EGR Cooler in Blue Finish | 2004.5-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax LLY

Sinister Diesel

Sinister SD66EGRC045BLU EGR Cooler in Blue Finish | 2004.5-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax LLY

SKU: SINSD66EGRC045BLU
$419.99
Tuner DT8120010101000 Switch on the Fly Tune incl EFI Live Spade | 2004.5-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax LLY
Tuner DT8120010101000 Switch on the Fly Tune incl EFI Live Spade | 2004.5-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax LLY

Duramax Tuner

Tuner DT8120010101000 Switch on the Fly Tune incl EFI Live Spade | 2004.5-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax LLY

SKU: DMTDT8120010101000
$1,098

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2004.5-2005 6.6L Silverado & Sierra 2500HD/3500HD

Power Lift Shop All

The 6.6L Duramax LLY under the hood of your 2004.5-2005 GM Sierra/Silverado 2500/3500 may be one of the best and most efficient engines out there, but even the toughest trucks have some power and performance waiting to be unleashed through various performance modifications. Here at Alligator Performance, we carry a selection of cold air intakes, tuners, fuel upgrades, and turbo upgrades to help you get the most out of your diesel engine. Many of these upgrades like the cold air intakes and fuel upgrades even help promote component longevity so you can enjoy long-lasting and consistent performance without compromise. After you've added a few engine upgrades to your custom build, be sure to check out our premium 2004.5-2005 GM 6.6L Duramax LLY Transmission Upgrades to compliment the increase in power you're throwing down! GM Duramax Fitments: 2004, 2005 GM 6.6L Duramax. Submodel Fitments: WT, Custom, LT, LTZ, High Country, 1LT, 2LT, Pro, SLE, SLT, AT4, Denali. Some exceptions apply, please see individual product pages for specific fitments.

GM Duramax>2004.5-2005 6.6L LLY
Tuners & Monitors
Cooling Upgrades
Head Studs & Main Studs
Rods, Pistons & Cams
Heads & Valve Train

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