Derale 13633 Plate & Fin Transmission Cooler Kit 5/8" Inverted Flare

Heat is what kills an automatic. Every ten degrees you pull out of the fluid roughly doubles its service life, and a factory in-radiator cooler alone cannot keep up once you hang a trailer off the hitch or run a built transmission hard. The Derale 13633 is a Series 8000 plate and fin auxiliary cooler kit that mounts in front of the condenser and runs the transmission fluid through a dedicated core before it goes back to the pan.

The core is furnace-brazed aluminum with embossed turbulators pressed into every tube. Those turbulators tumble the fluid as it passes through instead of letting it slide along the tube wall, so more of the oil actually contacts the cooling surface and sheds heat. The whole assembly weighs about 5 pounds and the kit ships in a 25 x 11.75 x 2 inch box.

What makes this the 13633 specifically is the plumbing: it comes with 5/8-inch inverted flare fittings, the same threaded flare connection used on a lot of GM and Dodge factory cooler lines, so you can tie into steel line without cutting to rubber hose if your setup uses that fitting. If your lines are barbed for hose, look at the NPT or hose-barb version instead. The kit includes the cooler, fittings, and a nylon-tie mounting kit to secure it to the radiator or condenser.

This is a universal add-on cooler, not a direct-fit replacement for a specific vehicle radiator cooler. Plumb it in series after the factory cooler for the coldest fluid, or as a standalone on a trans that has no factory cooling. Good insurance on any truck that tows, plows, or runs a performance build.