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XDP Xtra Cool Direct-Fit Transmission Oil Cooler XD309
PART#
XD309 | SKU XD309
★★★★★
Vehicle Fitment For:
2001-2005 GM 6.6L Duramax LB7/LLY
See full application list below
$235.95
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Description
The XDP Xtra Cool Direct-Fit Transmission Oil Cooler XD309 is a direct upgrade for the factory transmission oil cooler in your 2001-2005 GM 6.6L Duramax LB7/LLY. XDP’s Xtra Cool Transmission Oil Coolers are made using techniques borrowed from the HD and semi-truck industry to provide you with the ultimate in strength and durability. Built for more than just increased strength, the XD309 features a high-efficiency core that is specially designed to maximize transmission cooling potential over the factory unit. Each kit comes ready to install with the needed fittings, brackets, and hardware to make this a bolt-on installation for your GM Duramax/Allison powertrain.
Features:
- Direct-Fit
- Replaces Factory Cooler
- Upgraded Design For Increased Durability
- High-Efficiency Core To Maximize Cooling
XD309 Specifications:
Core Width: 12-1/2"
Core Height: 7-3/4"
Core Height: 7-3/4"
Core Thickness: 2"
Overall Length: 16"
Cooler Fittings: 7/8-14 UNF
Application Notes:
XDP cannot guarantee fitment with all aftermarket transmission lines.
Please match aftermarket lines with the cooler fittings specified above.
Manufacturer Warranty*:
2 Year / Unlimited Mileage
2 Year / Unlimited Mileage
Instructions & Tech Info
Installation Info
Reviews For XDP XD309
Verified Buyer
Does not look like the pictures
Nathan (VA) | March 15th, 2026
The radiator I got was steel. Very heavy. Seems to work ok, my transmission runs about 50 degrees cooler now.
Works great!!!
Ryan (Nau) | November 7th, 2025
Had this installed for over 5 years. Works great, runs a lot cooler, especially in summer while towing. Buy it.
Verified Buyer
Xtra cooler cooler
John (NJ) | December 6th, 2024
This cooler fit right into the factory mounts, lined up well and seemed plenty tight after all the mounting points were tight. I also upgraded to the hose kit. The transmission runs cooler than the original.
Verified Buyer
Trans cooler
Jack (Lillooet) | November 26th, 2024
Works amazing however it doesn’t come with an X on the part itself as shown in the photo.
Verified Buyer
XD309 excellent!!
Titus (TX) | October 25th, 2024
Top quality. You get all of your flow through this cooler. Very Happy with the product.
Awesome cooler for the price
Farmer dan (Illinois) | September 6th, 2024
Been waiting a yr to post a review.. well here it is.. it’s FANTASTIC. Easy to install, was seeing constant temps of 180-200 pulling a 30ft gooseneck weighing about 18K lbs loaded. Now my gauge barely gets over 150-160.
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Frequently Asked Questions
Is this a bar and plate style cooler?
No, the XDP Xtra Cool Direct-Fit Transmission Oil Cooler XD309 is a tube & fin design.
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Specifications For XDP XD309
MPN
XD309
SKU
XD309
GTIN
856217008489
ID
34756
Manufacturer Name
XDP
Shipping Weight
9.00 lb.
Shipping Length
19 in.
Shipping Width
14 in.
Shipping Height
4 in.
Fuel Type
Diesel
Manufacturer Warranty*
2 Year / Unlimited Mileage
Prop 65
WARNING: Cancer & Reproductive Harm - P65Warnings.ca.gov
WARNING: Cancer & Reproductive Harm - P65Warnings.ca.gov
Cross Reference #
15170221, 89040217, 20880895, GM4050106
Internal
L28R18
ITEM ADDED TO CART
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Product prices marked with an * may require additonal fees, such as a core charge, which will be displayed in the cart.