Yes. I'm sure. The flight I'm on is NW 1731 DTW-STT (Feb 2 08). It's definately not a codeshare with anyone (as far as I know). And the DTW-GCM is flight 1796 (Mar 22 08) which is a codeshare w/ CO, but it's on NW metal.
I can't speak for the flights out of EWR...