i have a1993 chevy 5.7 used to be TBI. i installed msd distibuter,and cdi box. Now have transmission in limp home.no rpm signal to the old engine ecu,i have tried the brown tach output wire,to the original white tach wire that went to the coil. this makes the tach. inthe truck work,but no signal to ecm which means no shift. anybody heard of the answer? I read in one forum that this particular ecm is the one to use for a stand alone for computer.