ECU,s Can you swap a 4 pin inplace of a 5pin?

I just swapped my ignition to electronic in my 66 Dart with a 360.The harness I used was from a 73 Swinger donar car,and is the 5 pin with 4 peg ballist.The ECU works but looks kinda grungy,rusty and I have two 4 pin,one is orange the othere chrome.Can I just plug the 5 pin (female)plug into the 4 pin ECU(male)?Which one is better?Orange or chrome?Thanks