I'm not surprised at all that a "remanufacturer" didn't bother to actually, yanno, remanufacture the CCM. The only way they could do that correctly would be to request information from you prior to shipment, which they obviously did not do. This leads to a huge issue in that anyone who uses a reman from that company would be committing odometer fraud at worst and have a branded title at best. Big freakin' yikes. So for your second unit, attempting to locate the reman terminal as well as all the requisite memory locations for a Mode 5 request might actually be worth it.

But for CCMs that are still good and still in a car, I don't see the point. I agree that for those, it would be a waste of time and energy. The only reason to mess around with that would be to do something nefarious, so it's probably best left alone.

On my end, I've worked out a test program that should allow me to inject arbitrary data into the ALDL port and override the dash. I'm working on the Arduino code now, so hopefully in the next week or so I'll be able to test it by just unplugging my PCM, plugging the Arduino into the ALDL port, and then turning a knob on my potentiometer to set the speedometer on the dash to whatever I want. I've never done tight timing serial comms before, so it'll be a fun exercise. And if it works, then we know that we can make anything work with the CCM going forward. So if someone had, say, Holley EFI, and wanted their dash to work, no problem. Cheapie Arduino board, set your outputs on the Holley to those needed for the datastream, have Arduino interpret those outputs into the datastream the CCM expects, and go.