I don't know if this is what the OP is thinking, but for me, it would be nice to be able to pull a part from a newer Ford to upgrade an older Ford, regardless of who the part manufacturer is. In the case of brakes, sure a caliper supplier will make a part for Ford, Chevy, Dodge, etc, but the configuration/bolt pattern and the like are often different, so in that sense, the parts are make specific.
I think the opposite is true for European cars, where you can swap many parts between makes such as Porsche, Audi, and VW - and find the parts for an older Porsche a lot cheaper by looking at VW parts.

In upgrading, I usually think make specific, and if that doesn't work, I don't have a problem going to other makes to accomplish the upgrade (though I have a problem with putting a Toyota steering box on my Ford... ) )