Question about getting parts
 

So I have a 97 GMC Sierra and yesterday there was a fitting that connects a radiator hose to the engine block that broke on me. I dont think this is a part that i can walk in any auto parts house to pick one up and even if so I couldnt easily tell them what part. Is there a good web site that shows all the parts and you can order them?

Rad hose or heater hose?
The rad hose fitting is the thermometer housing, it has the thermostat inside of it. If a heater hose, I guess its called a nipple. The dealer can get it. I would just go to an auto wrecker and grab one for a buck or two

You have several options. I would call auto parts stores and check. I also get my parts from junk yards that allow you to pull your own parts, as they are cheap. If I buy online, however, I usually go to Rockauto.com. They've got good prices, great selection, and have never had any trouble with buying or returning items.

Did any kind of fluid leak out when this part fell off ??? Was it antifreeze/water or tranni fluid or AC gas?? If the piece full OFF would it be possible to take the piece into your nearest dealership to show them?

I did a Google searched for a parts break down of your cooling system but wasn't able to find anything that might be helpful.

Sorry I wasn't able to help
Keep us up dated on your search

It is definitely something to do with the cooling system since it was overheating when I noticed. I checked out the rockauto.com and I think I found the part and it is pretty cheap. Ill try that out. Thanks for you help guys.