[Fat Charlie]

There are too many computerised parts that are specific to models and options that the aftermarket won't touch them.

I love looking up the older ones from before VIN filtering: What trim level? 2 or 4 wheel drive? What engine, transmission, and transfer case? Federal or California emissions? I can have 20 or so different choices for one model in one year.

Can you really see Napa having an aisle full of ECMs, another with TCMs and another with PCMs? BCMs, SCCMs, HCUs, WIN modules and airbag modules would require another store entirely and only scratch the surface of that they would have to have in their systems. It's not worth their time to chase that business.

Sure, the OEMs try to capitalize on it. You want a remote start? Get a car that comes with it or pay through the nose to have it installed and enabled at the dealer. Ditto with trailer brakes or a radio. They use it to support their price structure and gain a little accessory spending- but the accessory spending is more about getting people to come back to the dealer at least once before they need to buy another car.