I was wondering if I could cut the catalytic converters off of my expedition without messing up the o2 sensor? or Maybe somebody knows where the o2 sensors are located?

and why do you want / need to cut off the converters? is this a replacement for a bad cat? or do you just want to get rid of the cat's?
i beleive in most if not all states this would be illegal? not 100% sure.
i think there's more then 1 O2 sensor, 1 in front and 1 behind the cat.
myself, i would go to a good muffler shop, they have all the right equipment to do the work.
hth
Rick, Ore

the o2 sensor is at the end of the headers . but you would not pass emissions

It is illegal and it is a $10,000 fine if caught doing this if done at a shop.Do not remove a the cat on an OBDII vehicle or the service engine light will be on all the time.

As was stated, eliminating the cats is illegal. For myself I would rather go to a good muffler shop and have them install the high-flow cats. Expensive? yes but they are legal.