2005 Chevy Silverado Repair: Thermostat Problem & Coolant System. Replacing.

My thermostat has been stuck open for about the last 18 months on my 2005 Chevy Silverado. Today was finally the day that I fixed it. Anyone who has ever worked on their vehicle knows how much of a pain in the rear that it sometimes is to get to the proper parts/bolts/nuts/etc. Chevrolet/GM is not stupid, they make repairing their vehicles as difficult and time consuming as possible for two good reasons.
One reason is because most people will not even try to do it on their own. The other reason is so that their service centers will be able to charge for more hours to repair it. Well foohy. I did it myself and saved about $100. The thermostat (with built-in gasket) can be bought at an auto parts store (I went to Autozone) for about $12. The biggest pain with replacing the thermostat was getting to the nuts to take off the housing. I had to remove several other parts in order to be able to reach the nuts with my socket. I drained a little coolant and also spilled a bit on the ground. The whole process took me about 90 minutes but it was my first time so if I had to do it again I could probably do it in 45 minutes. My engine light is still on, but I think it will go off after driving about 15-20 minutes (it re-checks itself every 15-20 minutes or so). (edit..it went off in 15 minutes) Before I replaced the thermostat, my temp gauge wouldn't register above 180F and it took quite a while for my heat to warm up. Now, my gauge is at about 205F once the engine is warmed up. The service division is about the only thing that keeps most auto dealers in business. Ford just announced record earnings, is Chevrolet next? Not if I have anything to do with it.