F-550 weighing in at 14,000 pounds with tools and crane. Runs like a champ but had lots of problems early on (new turbo, radiator, exhaust sensors) but I found the best Ford diesel shop in NC I'm sure. It gets 8-9 mpg but it will pull anything and do it with a smile. I love it, but I wish it got better mileage.
It's OK to try and fail.....but never give up.