Yes im an idiot. My coolant system was really rusty due to old hoses. I was flushing the system everyday for about a week and a freeze snuck up on me and I completely forgot.
Anyway the freeze plug pushed out of the back of the head. I was wondering how much force it takes to push one in. If it doesnt take much I am going to attempt to knock it in with a broom stick through a clearance from the underside of the truck.

 

I'm sure that will never work. It's tough enough to install a freeze plug when you have plenty of room. They make a rubber plug for just such situations as yours. You set the plug in place and tighten a bolt. If you have room to get back there with a wrench a rubber plug may work for you.

 

The way I installed freeze plugs in the past was to warm the engine to expand the hole, remove the leaking plug while keeping the new freeze plug in the kitchen freezer. It will slide in easily at first because it has shrunk from the cold. I then hammered it in the rest of the way using a piece of wood the size of the plug and a hammer.

In your case, you may have to remove the head.