A 5.4 with any kind of care should go 200K. As far as the tranny, 4R100's are what get 500+ lbs of torque from a Powerstroke to the wheels. I think.
I bought my '01 7700 (5.4) last October. It had 90,000 on it then. It turned 107,000 about three weeks ago. Here's a list of what it's needed in 17,000 miles.

1. Front hub brg. (Easy job)

2. Take off IAC valve, spray WD-4D in it, work valve back and forth, reinstall. (10 min.)

3. Replace leaking manifold gasket, which I think someone started and gave up on when they broke a stud. ( Not difficult, but time consuming at about 3 hours)

4. replace a license plate bulb.

5. 1400 gallons of gas!!

I have no plans of giving this truck up. For the price I paid, I can buy a new reman Ford engine, and still have paid less than another 7700 they had with 54K on it. I like this truck more than any vehicle I've ever had. (Except my '63 Mercury)
In short, the list of repairs didn't really relate to the engine, other than the manifold gasket, which is no fault of the engine. 5.4's didn't make it onto the list of top ten engines for no reason. Rob