I have a 1988 Chevy truck and I replaced the heads and now I have a plug where my temperature gauge sensor use to go and it has a plug in it and I get seem to get it out any ideas. Ill post a picture if needed

Yes, a picture would help.

http://i98.photobucket.com/albums/l242/rayne3rr0r/IMAG0099.jpg

If an open-end wrench won't work, Sears sells sockets for 4-sided plugs. Also, a 6" pair of long nose Vise Grip pliers may work. Another option is to use a spline socket or spline wrench.

Well its inward not out I have to stick something in it to turn it

You don't think any of these options can get a hold of it? It doesn't look like a show-stopper, to me. If you can get a hold on it at all, it should be your's. I think even a quality open-end wrench, going in at a steep angle, could get it. If push comes to shove, drill it and use an Easy-Out.

I have tried a piece of harden key stock and it won't budge even with soaking in penetrating oil

Tap it first, to try and break it loose from its mount; apply PB Blaster or Kroil, letting it soak; then, apply heat to the area surrounding the plug. Apply a "cheater" bar to the stock, to increase leverage. If this doesn't work, drill it, install an Easy-Out, and remove it. I wish I was there.

Depeneding on the part of Texas I might invite you over for a beer okay I will try that