need to replace downstream O2 sensor

It is mounted after the catalytic converter on the appropriate bank. It may be a bit tough to access, and the threads may be binding or seized. Hard to say until you try. Standard tools are used. You can find great repair manuals with step-by-step instructions, diagrams, parts locations and other important information for a nominal fee here: http://bit.ly/mitchell_repair_manuals_online Or http://bit.ly/AllData_Repair_Manuals_Online