hi am wondering which of the two tranny lines is the tto and return line the top or bottom im really stuck!! someone put a inline filter on the top line and im looking to replace it but i need to know the flow direction
2001 4.3l 4dr

 

Top is return bottom is output

 

On the 700R4 the bottom fitting on the right side of the transmission is the "out" line to the cooler and the top fitting is for the return line from the cooler.

I have mine set up so the line from the bottom fitting goes to the top of the radiator cooler. Then a line exits the bottom of the radiator cooler and goes to a remote transmission filter (screw on type -- I also have the internal filter installed in the transmission). From the filter the line goes to the top of the auxiliary cooler. Then there is a return line from the bottom of the auxiliary cooler back to the top fitting on the side of the transmission.