[NCHornet]

Originally Posted by dieselcrawler

Normal running, I don't see over 160. However, the other day, I took a empty box trailer across the hill to my friend's, I'd guess the trailer it'self is about 1500 to 2K empty, and by the time I got back home, the trans gauge was at 200. That's back country roads, gravel, mixed broken pavement, hills, 20-40 MPH. It was about 65-70 ambient temp. Total round trip was about 15 miles... kinda surprised me that it got that hot... but never got the tork converter to lock up due to the speeds... that could have alot to do with it.

If the TC wasn't locked up you were really working the trans under those conditions. It is easier for the trans to pull a 12K trailer at highway speeds than a 2-3K trailer under 40 mph with TC unlocked. I would still install the 6.0 cooler if you plan on towing often.

NCH