I had put a post on a while back in another forum about which transmission cooler to use and i am still uncertain?? I ordered a cooler by mail and it is a 10 row cooler and the cooling tubes are 1/2" according to the box, but the openings look like they are 3/8". Its copper! When i started to install i realized that the lines on the truck were not the normal 3/8" that i am used of seeing, and i am not sure if i can send the new cooler back now. Will it cause a pressure problem using this large cooler with the smaller openings? I am switching to synthetic fluid also, and when i can afford it i am going to purchase deeper transmission pan. The transmission was overhauled before i got truck about 10-20,000 miles ago. I installed a perma cool remote transmission filter and temp gauge about a month ago and can now monitor the transmission temps and they are running 220-240 degrees today empty (especilly high in traffic)with the ambient being 95 or so. I towed 6000 lb alumalite the otherday and at times temp reached 260. I was doubting whether the gauge was accurate so while towing and seeing 250 degrees i pulled over and touched the remote filter that is right before the cooler and it was screaming hot to the touch and after idling 5 min. or so was a lot cooler. Could the old cooler be partly plugged up?? Maybe they didn't flush it or replace it after the old transmission was toasted?? Someone suggested using an engine oil cooler since the openings are larger?? Can you have to large of a cooler?? I would appreciate any info since i really need to get this temp down and am setting on a $60. 00 cooler i'm not sure i can send back since it was installed for a short time but no fluid applied to it. I had the transmission flushed and serviced about 4,000 miles ago, and it stays full of fluid. Sorry for the long post but i need to find out what my problem is befor i toast transmission!! Thanks, Tim.