Problem replacing O2 sensor after cat. on 2000 SR-5

I've heard that the O2 sensor was one of those fixes that is easily done and stupid to pay a mechanic $300 for. Bought the sensor, got the truck on jack stands take a look and the before cat sensor is facing down, easily accessible, and looks ridiculously simple. I take a look after the cat at the downflow sensor, there's a metal plate making it impossible to reach from the close side attached to the 2 bolts on the sensor so you HAVE to reach it over the top of the pipe making it impossible to fit any kind of wrench there. Not only that the wire trails up and INTO THE BOTTOM OF THE CHASSIS before the connector. There's a rubber gasket on the body that looks like it would need replacing if I rip it out and who know how far in the connector is. DAMMIT this pisses me off so much. From what I read the upflow sensor hardly EVER needs replacing. Anyone replace the after cat one on this truck before?

2000 Tacoma SR-5 4 cylinder 2.4L extended cab manual

 

Connector is under the carpet against a reinforcement. Need to remove the sill plate to get to it.

The best way to remove that sensor is cut the shield off to get to the nuts. More than likely the nuts are seized and will require a torch to massage the nuts to get them off. Up here in Maine. Nothing ever comes off correctly and the nuts are always round and rusted solid. If you have no experience get someone that does cause breaking a stud on the pipe will make you say words you might not have known. I've changed plenty of them and it's never an easy replacement.
Seen a lot of guys break the studs off and then it's a major cluster to try and save the pipe.

 

Thanks, I appreciate your advice. I will pay the money and save myself the nightmare. Really wasn't expecting this much trouble for this job. Good thing is my smog isn't due until next May.

 

And now you know why a GOOD mechanic will charge you a FAIR price to do that job. lol