At my work, Kallita Charters, we have a "tug" that we use to tow Learjets with. It has a /6 in it and has more than enough power to pull 16,000lb airplanes. Heck we have pulled a lockheed electra (Navy P-3 Orion) Im guessing 60-75,000 lbs?
Slant 6's rock!!!
5th