Yes, I would say the float is bad. There is a metal float in the gas tank that the gauge uses to read the fuel level. Sometimes this float wears out, holes develop in the float, and it fills with fuel, and sinks. That's why it could always read 'E'.
It's a pretty common problem on high mileage Explorers. My friend has a 93 XLT with about 140,000 and his fuel gauge is stuck on 'E' too. Plus check out the 'high mileage explorers' thread here and it will be mentioned there too.
If the float is indeed your problem, there is a link describing the fix on this site; the link is on the 'Explorer Owners Maintenance Reference Page' under the 'links' section of this site. It involves dropping the fuel tank and replacing the float. I believe the float is an item that is sold separately from the fuel pump itself, which is good. That means you won't have to buy a whole new fuel pump, just the float. Problem is, it's some work to drop the tank. Or you could cut a hole in your truck's floor above the fuel tank and go in that way, and put a little door in so that you can easily get to the pump area in the future...that's what one of my Bronco II friends did on his truck.