I don't think Ford ever made an F250 that can't tow a 7500 pound trailer.
How well it does it depends on a few things. Gear ratio is one of the biggest factors.
Gear ratio is most commonly either 3.54 or 4.10. 4.10 is lower, revs the engine more, and is better for towing.
Bigger is better in the engine/trans department. Diesels are the universal best choice from a performance/durability/MPG standpoint. Gas engine trucks are a lot cheaper to buy and usually cheaper to maintain, but they are weaker and use more fuel.
It wouldn't hurt to look at F350s instead of F250s. You pretty much can't go totally wrong with a one-ton for pulling a trailer. Just do not buy a Ford 6.0 diesel!!! Buy ANY OTHER Ford, if you want a Ford. Don't do it, don't do it, don't do it!