Chevrolet Repair: Cooling system thermostat, chevy astro, temperature guage

Question
I have a 1996 Chevy Astro 6cyl AWD van.  The engine over the past several years does not register even past the first marker on the temperature guage after full warm-up.  This is great in the summer but during the cold winters in Salt Lake City, it produces very little heat from the heater.  The cooling system has not been serviced for quite a long time and I thought I would try a new thermostat to see if that would help the heater problem.  I bought one along with a new gasket yesterday at the auto parts store but was disappointed to find that the thermostat is not located under the radiator cap as I had hoped.  Is it located in a place where I (pretty minimal experience and tools) can acess it and replace or is this something I should take it to a shop to have done?
Thanks in advance for your suggestions.
George Griner

Answer
George,
Sorry for the late answer, but my computer has been down. I would take it to the shop, they have the proper tools for this. It would save you alot of time.. They dont make vehicles like they used to.. Try Living in Minnesota where the temps can reach 60 below with the wind chill.. Thanks,, and good luck..