I have just purchased an external transmission oil cooler for the roadster pickup, and the recomendation is that it be hooked in series with the cooling loop in the bottom of the radiator, downstream from the radiator, which would be in the return line leading into the turbo 350. On a turbo 350 the 2 oil cooling ports are vertically aligned, one above the other. Does anybody know which of these ports is for the return line?