rick 1/1/2013You might be asking about the tranny cooler I think . Cars with a auto tranny have 2 steel lines that go from the tranny to the radiator . The cooler itself is in the radiator . Bigger trucks ( 3/4 and 1 tons ) have an engine oil cooler also for towing . And an extra tranny cooler . Most cars don't need this . Not many Lincoln's towing a 30 foot 5th wheel trailer . Hope this helps .