It is very likely that your 2002 SUV came with the Old Style Gerotor Oil Pump that featured a very shallow insert point for the Oil Pick Up tube where it mates up to the bottom of the Gerotor Oil Pump...bolted into the Timing Case Cover. Back then... what was happening involved either the complete flattening out of the Blue O-Ring... or cuts, nicks or tears that occurred in it when poorly installed when the motors were first assembled was causing a failure of the Oil Pump Pick-Up Tube to draw motor oil in from the bottom of the crankcase.
The later versions of this pump featured a deeper extension of the tube and an "Orange Seal" that covered the entire bolt hole and flange and that holds the pick up tube inside of the newly designed pump. These Atlas engines can develop and require as much as 65 PSI of Oil Pressure that equates to moving 7 Quarts of Motor Oil from the crankcase throughout the engine at a rate of over 11 Gallons a Minute through the oiling system in order to allow the engine to stay alive and not seize up at nearly 6,000 RPM during shifts at speed.
So with the wonky oil pressure readings you are getting, coupled with the very scary noises from inside of the motor at the same time... either the problem involves a clogged Oil Pick Up Tube causing oil starvation... or there could be a suction leak as described above that will prevent the Gerotor Oil Pump from pulling in enough oil and possibly having air cavitation as a result.
Regardless of which of these is the case... unless you can take oil pressure readings via an Analog Oil Pressure Gauge and Copper Tube and Metric Adapter installed where the Oil Pressure Sending Unit is now located and prove that the engine is not starving for oil....
@Mooseman 's cogent advice should rule your actions about NOT running the engine until such a test can be done. The attached link and related images from my Photobucket support what is covered in this post and should give you much pause about how difficult the work will be to accomplish if you decide to do this job on your own:
http://s557.photobucket.com/user/60...ENGINEREPAIR/GM42LOILPICKUPTUBE?sort=2&page=1