Ooops, I thought you had the 6spd, 2007 F150 Lincoln LT still had the 4spd, got the 6spd in 09, Expy got in 07. :S I'll leave my post for the information
The LT is a trimmed out F150, you have the same 6 speed as the Expedition and F150, the 6r75 for 2007. The torqueshift was in 3/4 and heavier only. The 6R75 is sealed and has a long maintenance interval. I had a oil change shop try to insist my Expy needed to be changed at 30k even though I told them it does not have a torqshift and I was following Fords maintenance schedule.
There is a plug on the passenger side where the full tube would have screwed into. Unscrew it to check if it is full and condition of fluid. I have checked my fluid quality and level 3 times since new. Each time it has been full and the color and smell of the fluid was unchanged since the first time I checked it. Note, Mercon SP or LV does smell different than the older mercon V fluid. I now have 74k miles.
Unless the fluid is dark and smells burnt I would not mess with it. Also, from my reading these transmissions have a thermostatic control valve internal to the transmission, no way to bypass it, so a "flush" doesn't work. No torque converter plug either. So just drain and refill. It will change about 80% of the fluid. If you really want to, drive a couple hundred, and drain and refill again. BE SURE TO USE THE PROPER FLUID!! Mercon SP and LV have modifiers and ARE NOT compatable with the older types or universal types.