You can get most of the water out by draining the radiator & raising the rear of the truck real high. You should be able to drain the block. You can either remove the plug or the petcock & poke a wire up in the hole if it is pluged up. If you have ever pulled the head on an engine that was stuck real bad you will see you are waisting time fooling with it. They are full of corrosion. If you do free it up it won,t be any good. It,s probably time to pull it out & rebuild it.
