I've unstuck about 5 motors with out ever taking them apart!
All were tractor motors but the truck will likely be easier becasue the hood covers the intake and the exhaust goes down unlike many tractors that just have rain dumped down the cylinders.
Take out the spark plugs fill the cylinder with oil or better yet PB blaster. Wait a couple months and take a pry bar to the rein gear on the fly wheel and will likely come loose!
Work it back and forth a little clock wise then a little counter clockwise till it turns all the way over. Helps if you can get another guy on the front with the hand crank too.
