Am wanting to haul my boat with my 01 quad cab 3.9 Have installed hitch and wiring and am wanting to install auxillary tranny cooler. Does anyone know which of the lines coming from tranny to radiator is the return line? (Cant find it in the Haynes manual) Also How difficult of a procedure is this and how time consuming? Does anyone out there have any recomendations on a brand of tranny cooler? Thanks!!!!!!!

The lower line is the return in most cases.I used a Hayden oil cooler on mine.I think it ran around 60 bucks.It wasnt hard to do just hard to get to in spots.Took me around an hour.It should come with general instructions.Good luck