NW now has 3 753's and possibly a 4th has now been delivered. I do not know whether they actually have had modification work done by Boeing or not. However, they were never all pulled from service. They are still flying their daily schedule.
Okay- you folks must have disappeared from the forums for the last few weeks. Did you miss the huge arguments on whether or not NorthWest was keeping the 753 order? And on whether or not the 753 would eventually replace the DC-9-10s? And also- if and when NorthWest merges with Airtran, can they replace the 753 with 717-2BDs? And can you stick a Rolls Royce fan blade on a Pratt 2000? Yeah, a lot of the arguments were THAT ridiculous, but anyhow.
All of NW's 757-351s are "unsatisfactory" in that the Pratt engines are not capable of keeping the plane pressurized at some altitudes. AT LEAST ONE has been returned to Boeing. It is due for mods. We hope that all of this works out.
I do not know the answer to the original question.
NW has not sent any -300's back to Boeing.
NW will continue to accept delivery, approx 1/month
NW -300's will have P&W's
NW -300's do not have a pressurization problem- it is a computer configuration issue (EEC)-low power at climb.
You will start to see more of them now-MKE,PHX,MEM, just to name a few.
On another note NW decided to sent 1153 (DC-10-40) to the desert. There has not been enough charter work to keep it in service.
This leaves 1143 the last -40, It is used for charter work, and a possible spare until Jan 03