Excess heat is the #1 killer of transmissions. For individuals who tow, race or simply run their diesel hard, know that proper cooling of your transmission fluid is one of the most important things that you can do to increase the life of your transmission. 
PPE’s Performance Transmission Cooler is a bolt-on replacement part that lowers the fluid temperatures up to an additional 20 to 30 degrees over the stock unit. When the mainline pressure is increased with things, such as a high performance transmission kit, you end up with additional heat being generated, so we recommend a Performance Transmission Cooler in such s.
Features:

• Increased surface area provides 60% more heat rejection
• Installation takes approximately 30 minutes 

Fits:

2003-2005 GM 6.6L LB7/LLY Duramax Diesel (Connectors with Purple Clips)