If you get the truck jacked up, or better yet on a lift, you'll find the fuel line in front of the tank. There is a fitting there as well, but it may be wrapped under some sticky insulation, I can't remember.
It's under pressure, obviously. So pull the fuel pump fuse and start the trucks and allow it to run until it quits. The disconnect the two lines. Once you've got the apart, put your fuse back in and turn on the key. The fuel pump will pump your fuel out.
I can't remember without looking, but you may, or may not, need to drop the front half of the tank to reach the line. You may be able to just grab the fuel line under the hood and do the same thing.
One last idea is to remove the filler hose from the tank. On the tank there is a one-way valve, so gas is not going to come pouring out once the hose is removed. Get a bucket under the tank and use a screwdriver or small rod to flip the one-way valve up and gas should flow. If the gas level is below the fill line level, use a small tube to siphon the gas.
