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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Merchant 331304A Transfer Case Gasket | 2001-2010 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
Merchant 331304A Transfer Case Gasket | 2001-2010 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

Merchant Automotive

Merchant 331304A Transfer Case Gasket | 2001-2010 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

SKU: MAT331304A
$4.92
Merchant 10233 ARP Rocker Shaft Bolt Kit | 2001-2012 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
Merchant 10233 ARP Rocker Shaft Bolt Kit | 2001-2012 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

Merchant Automotive

Merchant 10233 ARP Rocker Shaft Bolt Kit | 2001-2012 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

SKU: MAT10233
$24.72
Merchant 10263 Oil Cooler Install Kit | 2001-2010 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
Merchant 10263 Oil Cooler Install Kit | 2001-2010 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

Merchant Automotive

Merchant 10263 Oil Cooler Install Kit | 2001-2010 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

SKU: MAT10263
$65.63
Merchant 10010 Air Bleeder Screw | 2001-2016 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
Merchant 10010 Air Bleeder Screw | 2001-2016 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

Merchant Automotive

Merchant 10010 Air Bleeder Screw | 2001-2016 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

SKU: MAT10010
$10.92
EFI Live LIC-FS2-VIN Tuning FlashScan V2 VIN License | Universal
EFI Live LIC-FS2-VIN Tuning FlashScan V2 VIN License | Universal

EFI Live

EFI Live LIC-FS2-VIN Tuning FlashScan V2 VIN License | Universal

SKU: EFILIC-FS2-VIN
$125
Fleece FPE-DMAX-OC-RED Oil Cap Red | 2001-2016 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
Fleece FPE-DMAX-OC-RED Oil Cap Red | 2001-2016 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
Fleece FPE-DMAX-OC-RED Oil Cap Red | 2001-2016 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

Fleece Performance Products

Fleece FPE-DMAX-OC-RED Oil Cap Red | 2001-2016 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

SKU: FLCFPE-DMAX-OC-RED
$39.99
Edge 98203 License Plate Mount Backup Camera For Edge CTS3 & Diablosport Trinity 2 | Universal
Edge 98203 License Plate Mount Backup Camera For Edge CTS3 & Diablosport Trinity 2 | Universal

Edge Products

Edge 98203 License Plate Mount Backup Camera For Edge CTS3 & Diablosport Trinity 2 | Universal

SKU: EDG98203
$277.95
ARP 900-0750 4.075 Bore Ring Compressor | 2001-2016 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
ARP 900-0750 4.075 Bore Ring Compressor | 2001-2016 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

ARP

ARP 900-0750 4.075 Bore Ring Compressor | 2001-2016 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

SKU: ARP900-0750
$97.13
ARP 100-7534 Hex Head Valve Cover Bolt Kit | 2004.5-2010 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
ARP 100-7534 Hex Head Valve Cover Bolt Kit | 2004.5-2010 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

ARP

ARP 100-7534 Hex Head Valve Cover Bolt Kit | 2004.5-2010 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

SKU: ARP100-7534
$105.53
$201.29
Wehrli 100699 Billet Heater Core Fitting with Hose | Universal
Wehrli 100699 Billet Heater Core Fitting with Hose | Universal

Wehrli Custom Fab

Wehrli 100699 Billet Heater Core Fitting with Hose | Universal

SKU: WCF100699
$73.72
SoCal Diesel 917371 Super Damper Diesel Harmonic Balancers | 2001-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
SoCal Diesel 917371 Super Damper Diesel Harmonic Balancers | 2001-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
SoCal Diesel 917371 Super Damper Diesel Harmonic Balancers | 2001-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

SoCal Diesel

SoCal Diesel 917371 Super Damper Diesel Harmonic Balancers | 2001-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

SKU: SLD917371
$464.31
Merchant 97321295 Lower Valve Cover Gasket | 2004.5-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax LLY
Merchant 97321295 Lower Valve Cover Gasket | 2004.5-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax LLY

Merchant Automotive

Merchant 97321295 Lower Valve Cover Gasket | 2004.5-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax LLY

SKU: MAT97321295
$76.72
BD Diesel 1057735 Throttle Sensitivity Booster | 2001-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
BD Diesel 1057735 Throttle Sensitivity Booster | 2001-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

BD Diesel

BD Diesel 1057735 Throttle Sensitivity Booster | 2001-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

SKU: BDD1057735
$277.95
Tuner DT1120010101009 Switch on the Fly Tune incl EFI Live Spade | 2004.5-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax LLY
Tuner DT1120010101009 Switch on the Fly Tune incl EFI Live Spade | 2004.5-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax LLY

Duramax Tuner

Tuner DT1120010101009 Switch on the Fly Tune incl EFI Live Spade | 2004.5-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax LLY

SKU: DMTDT1120010101009
$1,098
Edge 21501-3 Juice with Attitude CTS3 | 2004.5-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax LLY
Edge 21501-3 Juice with Attitude CTS3 | 2004.5-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax LLY
Edge 21501-3 Juice with Attitude CTS3 | 2004.5-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax LLY

Edge Products

Edge 21501-3 Juice with Attitude CTS3 | 2004.5-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax LLY

SKU: EDG21501-3
$1,299.95
BD Diesel 1036605 High Idle Control Kit for Trucks with Automatic Trans & Cruise Control | 2004.5-2006 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax LLY
BD Diesel 1036605 High Idle Control Kit for Trucks with Automatic Trans & Cruise Control | 2004.5-2006 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax LLY
BD Diesel 1036605 High Idle Control Kit for Trucks with Automatic Trans & Cruise Control | 2004.5-2006 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax LLY

BD Diesel

BD Diesel 1036605 High Idle Control Kit for Trucks with Automatic Trans & Cruise Control | 2004.5-2006 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax LLY

SKU: BDD1036605
$44.95
Merchant 98045060 Grade C Left Side Head Gasket | 2001-2016 GM 2500HD/3500HD 6.6L Duramax
Merchant 98045060 Grade C Left Side Head Gasket | 2001-2016 GM 2500HD/3500HD 6.6L Duramax

Merchant Automotive

Merchant 98045060 Grade C Left Side Head Gasket | 2001-2016 GM 2500HD/3500HD 6.6L Duramax

SKU: MAT98045060
$99.72
PPE 119000600 Coolant Bypass Tube - Water Pump to Thermostat Housing (Raw) | 2001-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
PPE 119000600 Coolant Bypass Tube - Water Pump to Thermostat Housing (Raw) | 2001-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
PPE 119000600 Coolant Bypass Tube - Water Pump to Thermostat Housing (Raw) | 2001-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

PPE

PPE 119000600 Coolant Bypass Tube - Water Pump to Thermostat Housing (Raw) | 2001-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

SKU: PPE119000600
$116.99
Wagler C6641 Billet Main Caps | 2001-2016 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
Wagler C6641 Billet Main Caps | 2001-2016 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

Wagler Competition Products

Wagler C6641 Billet Main Caps | 2001-2016 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

SKU: WCPC6641
$750
Wagler C6658 Street Girdle | 2001-2010 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
Wagler C6658 Street Girdle | 2001-2010 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

Wagler Competition Products

Wagler C6658 Street Girdle | 2001-2010 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

SKU: WCPC6658
$850
PPE 114025010 Check Valve Crankcase Breather Filter Kit | 2004.5-2010 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
PPE 114025010 Check Valve Crankcase Breather Filter Kit | 2004.5-2010 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

PPE

PPE 114025010 Check Valve Crankcase Breather Filter Kit | 2004.5-2010 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

SKU: PPE114025010
$44.99
PPE 114002000 Stainless Steel Remote Oil Filter Mount Kit | 2001-2010 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
PPE 114002000 Stainless Steel Remote Oil Filter Mount Kit | 2001-2010 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

PPE

PPE 114002000 Stainless Steel Remote Oil Filter Mount Kit | 2001-2010 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

SKU: PPE114002000
$125.99
Wehrli 100442 Billet Oil Fill Tube Cap - Clear Anodized | 2001-2025 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
Wehrli 100442 Billet Oil Fill Tube Cap - Clear Anodized | 2001-2025 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
Wehrli 100442 Billet Oil Fill Tube Cap - Clear Anodized | 2001-2025 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
Wehrli 100442 Billet Oil Fill Tube Cap - Clear Anodized | 2001-2025 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

Wehrli Custom Fab

Wehrli 100442 Billet Oil Fill Tube Cap - Clear Anodized | 2001-2025 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

SKU: WCF100442
$49.47
Wagler CRC6.6ST Street Fighter Connecting Rods | 2001-2016 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
Wagler CRC6.6ST Street Fighter Connecting Rods | 2001-2016 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax
Wagler CRC6.6ST Street Fighter Connecting Rods | 2001-2016 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

Wagler Competition Products

Wagler CRC6.6ST Street Fighter Connecting Rods | 2001-2016 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

SKU: WCPCRC6.6ST
$1,950

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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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