4 oxygen sensors on old catalytic, 2 holes on new Flowmaster c. converter

We have a 2001 Dodge Ram 1500 and purchased a Flowmaster direct fit catalytic converter and muffler. We were getting it ready for inspection and ran into a dilemma. The stock converter has 4 sensors, I am guessing 2 upstream, 2 downstream. The converter we ordered only has 2 holes, 1 hole before the converter and the other is after it. Supposedly, Flowmaster does not have an answer yet as to why there are only 2 ports/holes. So we are stuck. Does it need the 4 sensors to pass or can we go with 2? This really sucks that we didn't know this was going to be a problem until everything was installed. Thanks!