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Some parts places list a 4-prong ICM for my 85 and others list a 7 prong.
Not YOUR 85. Somebody isn't reading the catalog (computer?) correctly or know what he's doing. Four prong modules are for mechanical and vacuum advance HEIs. The 7 prong modules are for the ECM controlled HEIs. All EFI GM cars have ECM controlled ignition.
Why not pull it out and have it checked? Autozone does it for free, just make sure they run it through 10 cycles to get it hot. AND, make sure when you re-install it you put dialectic grease under it-or it will get hot and burn out.
Radio Shack sells a small (6.5 gram) tube of Heat Sink Compound for $1.99. This is enough to do an ICM.
It's part number 276-1372; their website lists it as "heat sink grease", but the label on the package clearly reads "heat sink compound."
You can use this, too, if you don't have di-electric grease or if the replacement module fails to include it in the packaging. Sometimes they do, sometimes not.