2002 GMC Sierra O2 sensors

Just wondering if it would be possible to swap the front and back O2 sensors?

Oxygen sensors all do exactly the same thing. The only difference might be in harness length and/or connector design. Check with a parts store and ask if the part numbers are the same. Why do you want to swap them? If the SES light is coming on now, it will come on after you swap them too, and it may or may not be the same DTC.