if your running a distributor,the grey module bolted tothe lower side with wiring goimg in and out.i went thru 1 coil a week and about 14 hrs driving,it wouldnt start.changed the coil and ok.went to the auto electricans and checked the coils,they where ok.ran the motor and checked voltage to coil---13.8 v,checking the tfi module,we found it breaking down---intermittly,i have a miss when it happens.