1989 Pickup Oxygen Sensor mounting nuts.

Help please! For Fathersday my children ask, what do you want dad? I said I need an oxygen sensor for the truck. Well lo and behold they got one for me. So today I decided to start to replace it. I soon discovered that the nuts holding the sensor in, where badly rusted and rounded to the point where there are no flats left for a wrench grab hold. If it isn't bad enough that the nuts where destroyed, the location of the sensor is positioned such that I can't even get a set of locking pliers on them. Does anyone have a solution for this repair. It's a 89 4x4 with a 22RE engine, short bed, reg cab. Their is only 1 sensor just before the CAT. converter. It is surrounded by a heat shield.

Thanks,
Jkubo

Can you drop the cat, or maybe loosen it enough to rotate it to get to the sensor ?

Well I did more than that. I removed the exhaust pipe from the manifold to the catalytic converter. It's in need of replacement too. This allow me to get access to the sensor using locking pliers to remove the rounded nuts. The new pipe will be here Tuesday with new hardware.

Thanks,
Jerry K