hi there, autosone sells a o2 sensor tool that worked for me, they had ywo different types and of course the second one i bought worked for me. it is a offset type socket, part #(25249) and brand printed on tool is (oem) 7/8" which converts to 22mm. this job will take harry houdini like magic in my experience. i have since replaced the exaust manifold (cracked bad) with one from a 740 turbo and moved the o2 sensor to the top of the downpipe close to the manifold. good luck