At $54,000 you are not getting a great deal unless the dealer extends the warranty or better yet includes an extended warranty for the truck. As a whole the 2011 and later Ford diesel trucks (engine, drivetrain, transmission, heating and cooling systems, brakes, etc.) have been exceedingly reliable.
I paid under $42,000 for my GM Duramax with less than 50 miles on the odometer and with the intermediate trim level and with every options package except the navigation package, and included with the truck was the backup camera, remote start, chrome running boards, GM bed liner, GM aluminum diamond plate tool box. The sticker price on it was $58,000.
People expect to pay over $60,000 for a diesel pickup truck and the dealers are only too happy to oblige. No vehicle provides more dollars of profit to the dealers than pickup trucks and with the $9,000 bump with a diesel engine and its transmission, they do even better.