I'm not familiar with Ruf beyond their inclusion in the Gran Turismo series, but are they actually distinct replicas of 911s, or are they purchased 911s (or sub

I'm not familiar with Ruf beyond their inclusion in the Gran Turismo series, but are they actually distinct replicas of 911s, or are they purchased 911s (or sub-assemblies) that are have aftermarket parts swapped, like Shelby-editions of Ford vehicles? Because if its the latter, then it's still a Porsche 911, just with Ruf branded parts attached.