Leaking transmission cooler lines are one of the most common issues on Duramax trucks. Factory lines can corrode, seep, or fail over time, leading to transmission fluid loss and potentially expensive repairs.

Stop Leaking Duramax Transmission Cooler Lines for Good

Speed Stop Auto Repair upgraded 5/8" Duramax Transmission Cooler Line Kit is designed to provide a reliable, long-lasting solution for Chevy Silverado and GMC Sierra HD trucks equipped with the Duramax diesel and Allison transmission. Whether you're fixing an active leak or replacing aging factory lines before they fail, this kit delivers the durability and performance your truck needs.

FITMENT Note : 

• If you have an aftermarket radiator, you will need M22 fittings instead of OE-style to JIC. This can be easily determined if your radiator has a hex-shaped fitting behind the OE-style transmission cooler fittings.

• 2001-2002 Allison transmission cooler inlet/outlet fittings had a smaller 3/4 inch thread diameter than later 7/8 inch units. If you think your transmission has been swapped with a later unit, you can measure the original trans cooler fitting in the transmission or reference the build plate found on the passenger-side of the transmission.