My '82 Elky diagnoses keep pointing towards the ECM, so i'm ready to blow some more money and buy a remanufactured one. So my auto supply guy tells me I need the O.E No. or he can't help me. My ECM is already a reman, looks really old, and has no O.E. No. on it. The line where it's supposed to be is blank. So now what? He says his books show two possibilities, but he has to have that number. What do I do now?! I've heard of guys getting these from salvage yards and they work. Are the two that the parts guy has interchangeable?