Tranny cooler that actually WORKS is about 50 bucks, and takes about 30 min to install. Stock cooler is NOT WORTH A CRAP. I have seen some trucks in the summer run as high as 200 towing NOTHING wqith the stock cooler. Mine runs about 145 to 150 running empty and 180 towing 18k. Cost of a decent tranny, about 2200 to 2500. Go get yourself a cooler and save your truck, and yourself a headache.