2006 Ford F-150 crew cab

I looking at buying a used F150 and was wondering how I could tell if the truck had a locking rear differential visually. Is that possible or would I have to put it in something loose and get on the gas. Also is there an easy way to tell if it has a tow package like a transmission cooler or would that be standard?

The information on this truck is limited. Thanks

AN 06 will sometimes come with the tranny cooler, depends on the package you purchase. One word of advise, unless you are towing allot of heavy equipment, stay with the 4.6 ltr engine. these are good, reliable engines. The 5.4 3 valves are having major issues with injectors failing and destroying engines. Your locker question, look at the ID tag on the diff. If there is an L (3L.55) That means limited slip, factory locking rear end.