Can anybody help me figure out which ECM I need? I havenít been able to figure out the Ford numbers and the dealership was no help. I have changed my transmission in my Ranger from a manual to an automatic. I need to figure out which ECM that I need. There are 6 choices available. My current ECM is # 3L5A-12A650-ADB. It appears that the only thing that matters is the last 3 letters. The truck is a 2003 XLT 4 door, 4x4 with 4:10ís.