6L80E/6L90E/8L90E Cooler Line Adapter Plate -6AN Billet

This is the billet aluminum adapter plate that lets you delete the factory GM cooler line connector on a 6L80E, 6L90E, or 8L90E and run your own -6AN braided lines instead. It bolts to the case where the OE quick-connect block sits, seals against the factory gasket, and gives you two -6AN ports for building custom cooler lines.

Fitment is all 6L80E, 6L90E, and 8L90E transmissions. -6AN is the same nominal size as a 3/8" transmission line, so it matches the most common AN cooler hose people already run. The kit comes with the adapter plate, two -6AN fittings, the factory-style gasket, and the mounting bolt, so nothing else is needed to make the swap.

The usual reason techs reach for this: the factory plastic cooler line connector is a known leak and failure point, and the OE setup routes trans fluid through the radiator where a coolant-to-oil crossover can kill the transmission. Swapping to this plate lets you route -6AN lines straight to a standalone cooler and drop the radiator trans loop entirely. It also cleans up an LS/LT swap where you are relocating or upgrading the cooler.

Part number 551121-6AN, machined from USA billet aluminum in Wichita, Kansas. Installs with hand tools once the case is accessible.