I'm pretty sure the ignition module on the '90 model is bolted to the distributor housing, but it takes a special socket to remove it. I don't remember the size for sure I think it's about 4.5MM or 5MM, but it has to be a thin wall socket to fit into the recessed area where the bolts are. You can tell them at an auto parts you need an ignition module socket for an older model Ford and they should know exactly what you need.