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Mishimoto 2003-2005 Chevrolet / GMC 6.6L Duramax (LB7/LLY) product view

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Mishimoto MMTC-DMAX-03SL installed angle on vehicle

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Mishimoto 2003-2005 Chevrolet / GMC 6.6L Duramax (LB7/LLY) core and end tank detail

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Mishimoto 2003-2005 Chevrolet / GMC 6.6L Duramax (LB7/LLY) packaging and included hardware

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LLY) Transmission Cooler - Silver

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Brand: MishimotoSKU / Part #: MISMMTC-DMAX-03SL

Regular price: $498.95
Regular price: ~~$549.00~~
Sale price: $498.95
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Subtotal: $498.95

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Mishimoto 2003-2005 Chevrolet / GMC 6.6L Duramax (LB7/LLY) Transmission Cooler - Silver

Subtotal: $498.95

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Overview

This Mishimoto performance cooler is a direct-fit upgrade for 2003-2005 Chevrolet/GMC applications covering Sierra 2500 HD, Sierra 3500, Silverado 2500 HD, Silverado 3500, Silverado 3500 LS. It replaces the weak points of the stock part with stronger materials and better flow or cooling so heat, boost and abuse stay under control on street and track duty. AutoTalent lists verified US-market fitment in the table below.

Why upgrade

There's no greater enemy for a transmission than heat. Whether your 2003-2005 Chevy/GMC 6.6L Duramax is a dedicated tow vehicle, hardworking fleet truck, or a daily driver with a liking for the drag strip, you need to ensure that your transmission runs cool. Luckily, Mishimoto has developed a direct-fit transmission cooler to do just that. Mishimoto engineers these kits around real chassis packaging, so hoses, coolers and adapters line up without fabrication on the listed years. Follow the published torque specs and install guide, reuse sensors where instructed, and confirm clearances if you run other supporting mods. Every unit ships with the Mishimoto Lifetime Warranty for as long as you own it.

Features

Direct-fit for all 2003-2005 Chevrolet/GMC with Allison transmission (LB7/LLY)
Stacked-plate construction for maximum durability and superior cooling
CNC-machined adapters make it easy to connect Mishimoto cooler to stock fluid lines or AN lines
174-percent greater core volume than stock cooler
192-percent greater external fin surface area over stock cooler
Patent number D900,161
Includes durable SAE J1532 hose designed specifically for use with transmission fluid

What's Included

Mishimoto Stacked Plate Transmission Cooler
CNC-Machined Quick-Disconnect to Hose Barb Adapters
Stock-style Quick-Disconnect Fittings
Transmission Hoses
Mounting Brackets
Worm Gear Clamps
Zip Tie
Mounting Hardware
Mishimoto Lifetime Warranty

Specifications

Part number	MMTC-DMAX-03SL
Brand	Mishimoto
Type	cooler
Engine codes	6.6L Duramax
Chassis codes	LB7
Shipping dimensions	30 x 15.3 x 4.8 in (76.2 x 38.9 x 12.2 cm)
Shipping weight	9.2 lb (4.2 kg)

Fitment Notes

Verified against Mishimoto US applications and dealer listing for 2003-2005 (5 rows). Years extended to 2027 where the US model remains in production.

Vehicle Fitment

Questions about fitment? Call (310) 231-0292 or text (310) 886-3111.
Year	Make	Model	Chassis	Engine
2003-2005	Chevrolet	Silverado 2500 HD	GMT800/900	—
2003-2005	Chevrolet	Silverado 3500	GMT800/900	—
2003-2005	Chevrolet	Silverado 3500 LS	GMT800/900	—
2003-2005	GMC	Sierra 2500 HD	GMT800/900	—
2003-2005	GMC	Sierra 3500	GMT800/900	—

Fitment

Year	Make	Model

Not sure? Text us your VIN and we’ll confirm.

Shipping & returns

Shipping: Orders ship via UPS, FedEx or USPS, from our facility near Los Angeles or directly from the manufacturer. Rates for many items are weight-based and shown at checkout. If you need it by a certain date, text us before you order.

Returns: Unused items in brand-new condition and original packaging can be returned within 30 days of the invoice date, with a 25% restocking fee unless otherwise specified. In some cases we can offer a lower fee with the balance as store credit. Shipping charges aren't refundable in either direction unless approved by AutoTalent.

Not returnable: special-order or custom items, and anything that has been installed, modified or altered.

Cancellations: free if the item is out of stock or we miss the ETA you agreed to. Other cancellations carry a 5% processing fee to cover card fees we can't recover. Special-order items can't be cancelled.

Damaged in transit? Report it to the carrier and to us within 48 hours, keep all packaging, and don't send anything back without our written approval.

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