o2 sensor help

yes I tried searching, but not having much luck

I have the stupid p0420 code and want to change both of my o2 sensors. I found the denso downstream on rock auto, but the only denso upstream says its for an auto trans only. Can anyone help me with a part number or another location to find the proper up stream sensor please

 

Scratch everything. Find someone with a scan tool that can look at your upstream and downstream o2 sensor wave patters. Upstream should be switching from rich to lean up and down in a fairly smooth waveform. The downstream should be a straight line... if it looks like the upstream waveform...you've got a bad converter.

 

I don't know of anyone local that has that nice of a scan tool. The truck has 255,xxx miles and the light was on for the sensor when I purchased it. Ran a tank of premium through on recommendation from a local mechanic and the light went off temporarily, put reg unleaded back in it and now the sensor wont go back off even with premium.