Hello, I am a first time site user. I have a 32' three axel trailer with a race car inside. The total weight is 13,000 lbs. I am pulling it with a 2002 dodge 2500 with a 5.9 cummins. I am really pushing the towing limit here. So, I am looking at a 2002 Kenworth T-300 'bobtail' truck with a Cat 3126 and 6 speed allison trans. The rear end is 4:63. How can I find out what the pulling power is of this vehicle before I purchase it and convert it to a 'motorhome'? Thanks, Rich