37-Row Transmission Cooler Kit for 7.3L Power Stroke

Thirty-seven row stacked-plate transmission oil cooler for the 1999-2003 Ford Super Duty and 2000-2003 Excursion behind the 7.3L Power Stroke. It ships with the hoses and clamps needed to plumb it, and the fittings are SAE J514 on 3/8 in line. Stacked-plate construction moves more heat per frontal inch than the tube-and-fin coolers these trucks left the factory with, because the ATF runs through flat plates in parallel instead of a single serpentine tube.

Heat is what kills the 4R100 behind these engines. ATF starts oxidizing above roughly 220 F, and every 20 degrees past that cuts fluid life roughly in half. On a stock truck pulling a trailer up a grade with the converter unlocked, pan temps climb fast and stay there, and the result is glazed frictions, a burnt 2-3 band and a dead direct clutch pack. A cooler this size is the cheapest insurance you can bolt to the truck, and it is standard practice after any rebuild on a truck that tows.

Mount it ahead of the A/C condenser with the inlet at the top so the ATF drains through the plates rather than sitting in them. Route the supply from the transmission outlet line, through the cooler, then back to the return - flow direction matters and the fittings are marked. Use transmission-rated hose only, keep the bends gentle so you do not kink the line and choke flow, double-clamp every joint, and check fluid level and inspect every connection for weep after the first heat cycle. On a truck that spends real time under load an inline thermal bypass is worth adding so the fluid still warms up on cold mornings.

Verify fitment before ordering - the kit is sized for the 7.3L Super Duty chassis and Excursion, and a different truck will need different line lengths.