40k Transmission Oil Cooler LPD47391, Low Pressure Drop

This is the LPD47391-style 40k transmission oil cooler, the low-pressure-drop stacked-plate design that is the standard upgrade when a factory in-radiator cooler cannot keep up with towing, a lift, oversized wheels, or hard stop-and-go driving. The core is all-aluminum and rated to 40,000 lb GVW, so it flows enough fluid to hold temperatures instead of choking the line the way a small tube-and-fin cooler does.

It mounts inline on the transmission cooler lines, in front of the A/C condenser and radiator where it gets clean airflow. Most installs either supplement or fully bypass the radiator cooler. On GM trucks (Silverado, Sierra, 4L60E and 4L80E swaps), Ford, Ram, and Nissan tow rigs, techs cut the steel cooler line, flare it or slide hose over it, and route both feed and return through the cooler. Prefill the cooler and lines with ATF before the first start so the pump is not pushing air.

What it fixes: heat is what kills an automatic. Towing or a heavy setup routinely pushes fluid past 210-240 F, which is where clutches glaze and fluid oxidizes. Owners running this cooler report steady 140-170 F under load, with smoother shifts once the fluid stops overheating. Real bench advice from the field: the included rubber hose and clamps are the weak point, so budget for a length of quality transmission cooler hose or -6AN PTFE line and better clamps, and use thread sealant on the fittings.

Kit includes the cooler, mounting brackets, hardware, and hose. Fits any vehicle running 3/8 in (11/32) transmission cooler line, gas or diesel.