When you're at the dealership, looking at new Ford F-150s, you'll have to choose between two bed lengths: 5.5 foot and 6.5 foot. The 6.5 foot is not a common bed length, which can make it difficult to spot in a crowd. If you're looking for a specific bed length, you'll need to pay careful attention to one key area of the trucks you see.
The trick to spotting the difference is highlighted by the bright green chevron on the image. Look at the gap between the back of the cab and the wheel well--when you do, the differences between the two trucks are far easier to spot! The two wheelbase lengths on F-150s are the short version, which is 145 in, and the long, which is 157 in.