On the 2.8l, there is only one ignition module, and it's inside the distributor. The whole system is GM/Chevy, early 80's vintage.

There is an ECU, which, if I remember right, can control the timing through two of the wires going to the module. The ECU will be mounted under the dash. It's an aluminum box, about 5" by 7" by 1-1/2" with two blue or grey multi-pin connectors on one end.

Make sure that the power stays on at the module while the engine is being cranked. A test light will help you check it. The ignition switch could be bad if it doesn't.

If you are checking for spark at the spark plug, also check it at the coil wire. If you then have spark, suspect a bad rotor, cap, or even the one plug wire you happened to check.

Also, check the coil wire, it's possible that i'ts fried inside. It should have some continuity through it, maybe 5000 Ohms per foot.

Some parts stores have ignition module testers, it's possible the one you got was faulty, or that the original one is still good.