GM C/K Pickup 1996-2000 Transmission Oil Cooler 918-259

This is a replacement automatic transmission oil cooler that matches the 918-259 part number. It is listed for 1996-2000 Chevrolet and GMC C1500, C2500, C3500, K1500, K2500 and K3500 trucks, and for the 1999-2000 Cadillac Escalade. The fitment chart shows some Suburban and HD models ending in 1999, so check your exact year and model against the chart before ordering.

It is a black finned cooler with threaded fittings and mounting brackets on each end. Measured size is about 11.13 in. long, 7.75 in. wide and 1.57 in. thick, with 0.75 in. fittings.

Why replace it: heat kills automatics, and trucks from this era that tow or haul work their 4L60E and 4L80E units hard. An external cooler that is packed with debris, bent up, or seeping at the fittings can't pull enough heat out of the fluid. The result is dark, burnt-smelling ATF, soft or late shifts once the truck is hot, and a shorter life for the clutches and seals. A cooler that is leaking at a fitting also drops the fluid level, which is one of the fastest ways to cook a transmission.

On install: flush the cooler lines before you connect the new cooler, especially after a failure. Debris left in the lines ends up in the new cooler and the rebuilt unit. Check the line fittings and O-rings, mount the cooler solidly, then run the engine and top off the ATF to the correct level at operating temperature.