firstly, hello. well, for starters, i tried searching the archives already with no luck. my question concerns the colors of the tfi modules themselves and their incompatabilities with each other. six years ago on my second stang, i had to replace the tfi. i didn't read the instructions considering it was straight forward and it did solve my problems. now on my fourth 5.0 my tfi failed the test so i purchased a new one (and not the cheapest available). i read the instructions for good measure and noticed specific regards to the color of the housing. it read as follows: grey can replace blue or grey; blue should not be used to replace grey: and of course blue can replace blue. well, the replacement for mine was grey but my tfi is white! ok, one more thing! the bottom screw was missing from the tfi when i went to remove it, so i got a replacement and whaddaya know, its pretty stripped. it does have a small degree of bite to it though. i replaced the tfi and got the necessary bolt and lined my dizzy back up to my marks. it runs really rich and stumbles hard and dies, kinda like its a bad tfi. i'll retest the new tfi soon but is it possible the tfi isn't being held down tight enough or do i have the wrong color . now, i've always noticed the different colors, but i had no idea there was a color correlation. sorry this is so long but i'm trying to be clear, trust me, i don't annunciate this much when i talk! can anyone help clarify this?