You really need the complete harness from the durango. Don't need the ECM pinout as much as a detailed schematic for the Durango AND the DART. Its going to be hard to get it to work right with the 904 tranny even if you go with the Standard shift ECM since it also looks for clutch engagement and other things. Plus, since the ECM is from a 4X4 its likely to give you fits even if you go with a 2 wheel drive 500 or 518. Get an ECM from a Dakota 2 wheel drive with the same engine, that will work. Major surgery to the cross member and floor if you do use the 500 or 518. Plan on a shifter with a rear entry cable also since there is no room for one to go forward like most shifters. It gets too close to the headers and melts! Here are some pics of what I had to do in order to get one into my Dart.
Larry