I recently cut out my old rusted exhaust from the merge collector just before the upstream O2 sensor, welded in a stainless 2-1/4" v-band and rebuilt the exhaust out of 2-1/4" 304L with a magna flow universal cat and a borla pro XS muffler. The fit is fine, the issue i'm having is I welded in two M18 O2 bungs (both upstream and down stream, not flange compatible) and now finding O2 sensors that are compatible with the 3.4 5VZ that do not have the factory mounting flange is difficult. I've tried removing the flange from the threads of the denso 234-4161 and an aftermarket universal walker, but I end up damaging the ceramic portion of the sensor in the process.
Anyone run into this issue before, or know of a threaded O2 sensor that will play nicely with the ECU for the 5VZ? Thank you for any and all help!