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Glad to be of help. No tool necessary but there are vacuum filler tools out there although not cheap. Before filling radiator, open bleeder screws 3 full turns. There is one on thermostat housing and one just above water pump on pipe assembly. Turn heater setting to full hot, fan off. When you see coolant without air come out close bleeder, then start engine and bring to normal operating temperature and bleed remaining air. Here's a video for bleeding although it's for a honda, it uses the same principal. http://www.youtube.com/watch?v=zUpXgAJ1gjU
Here's a link for a bleeder tool. http://www.youtube.com/watch?v=ZrQSl2ML_mc
Here's a forum link: http://www.gm-trucks.com/forums/index.php?showtopic=72461 If you continue to get air at the bleeder, there may be a problem such as a loose hose, bad thermostat, head gasket, or a worn water pump sucking air. It would be a good idea to pressure test the system to see if it holds pressure. If it is overheating or was overheated, it would be a good idea to get a tool called block check to test for combustion gases in cooling system. This will check for a bad head gasket.
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If there are no bleeder screws on it, bleeding is not necessary. You would fill it like in the video but without bleeder. Pressure test the system to see if it holds pressure for 30 minutes.
Here's a link http://autorepair.about.com/library/faqs/bl666c.htm