[vublt]

So I've grown a little tired of seeing my "service engine soon" light on every day for the past year, and it's supposed on because I have a bad O2 sensor. I want to change the bad sensor (apparently there are 4 are this engine and this is the 2nd one in the sequence). Oh, I have a 4.3. Vortec V-6. I've been told that I need some special tool to remove/change the sensor. I'm wanting to know 1) do I really need to buy/rent this removal tool, and if so, what is it? 2) Where exactly are the O2 sensors located? 3) What is the procedure for chaning them?