transmission cooler lines, rubber or metal?
The OE lines that come out of the tranny to the radiator and back are metal. It seems to me that if at the pressures and temperatures involved that if the manufacturer could have gotten away with rub...
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I had added a Hayden transmission cooler, in series, using Hayden connectors between the factory lines and radiator. This was ten years ago on a Silverado 5.3. I never had any trouble with the included rubber lines, but I did replace them 2 years ago after inspecting them. As mentioned before, you just want to make sure there are no kinks or restrictions in the hose and no rub points. I used pieces of heater hose cut down the middle and wrapped around the transmission hose and secured with zip ties to eliminate rub points.
