Your trans cooler is built into the radiator. Trans fluid goes through a cooler INSIDE of the radiator. The coolant cools the trans fluid. There is a leak in your trans cooler located inside the radiator, that is why the 2 fluids are mixing.

2 things you can do. Flush the radiator and cooling system VERY well, and seal up the trans lines on the radiator. Get an external trans cooler.

Or you can buy a new radiator and hook things back up like it came from the factory.

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