Oxygen Sensor on Muffler?

If i was going to change my muffler is there an oxygen sensor that i would have to transfer from the old muffler to the new. Im told that if i dont put the oxygen sensor in the correct place on the new muffler it could completely mess up my computer system on the truck. Is this true or can i just rip the old muffler out and then stick the new one in without worrying about anything?

Your O2 sensors are just before and just after the cat.