Plumbing for an additional filter:
I just checked on site...
Best would be to cut the old rubber return line at the passenger side connecting from the cooler (banjo 19mm Hex) to the transmission steel line (M14x 1.5 cone I guess). The rubber hose is OD 15mm
depending on the ID of that hose I could choose the Filter barb ... 3/8" Filter means that the barb is for a 3/8" (9,5mm) ID hose, correct? If the ID of the hose is about 9mm it would fit then.

Martin