replacing O2 sensor 1987 gasket??
 

I am replacing the o2 sensor is there an O -ring or a sealing washer that I should use, thanks JL

No, just like a spark plug--integral seal. Some use copper based anti-sieze. But JUST a whiff on the threads.

I just replaced my original cat with a MK premuffler on my 89 Coupe and there was no gasket on the O2 sensor.Spray a bit of loose nut and with a 22mm wrench it came off easily,just be careful not to twist the wires too much,although you are replacing the unit anyways...