Hey, just being ignorant, that is, not in possession of all the facts, doesn't mean we're stupid, does it? Sir Winston Churchill, British Prime Minister, said to America, prior to its entry into World War II, "Give us the tools, and we'll finish the job." The tool we need is accurate pertinent information, which I'm confident the EFI GearHeads have. Somewhere. The answer to the question, "How do you eat an elephant?" being "One bite at a time.", I guess we make progress (learn) one question at a time. The PROM (for Programmable Read Only Memory, I believe) chip is the removable chip inside the PCM (Powertrain Control Module) a.k.a. ECM (Electronic etc.) ECU (...Unit) and "the aluminum box in a hard to access location inside the car that all the wires plug into." And I think when I read about "Calpak" it means the PROM. I welcome correction and clarification.