That probably includes all the hoses and the heater core as well. Probably also depends on what "size" rad your truck came with too. I know there was a heavy duty one and a standard one early on.
IMO, you can never get "all" the coolant out by just draining, even if you could get to the pass side drain.
When I do mine, I drain the rad, fill it up with water and leave the rad drain valve open. Run engine and watch the water level. When the t'stat opens and warm water begins to come out the drain, shut engine off and let drain. I'll do this a couple times until it can run for about 15 minutes and only clean (hot) water comes out.
Drain rad, close drain and put in favorite flush product. I like the kind that says to only run at full operating temp for 10 minutes or so. I do this by driving around the neighborhood some and letting it run in the driveway. I then shut engine off and let it cool down for at least an hour.
Then I do the above process all over again to get that crap out of the system. It's amazing how dirty the water is after this flush.
I finally just add 2 gallons of AF to the rad and then top off the resovoir with 50-50 mix and run it again for awhile. Keep an eye on the level and the temps for the next couple days and it's good for another 18 months!