Well on a 92 400E with ASR there is no distribution block. Single line goes all the way from the front to the right rear and another one goes from the front to the left rear.

My assumption is this is necessary for the ASR as it needs to apply brakes to only one wheel.

Once I get tooled up to do flares properly I will probably use the Copper Nickel brake line on any issues in the future. It appears to eliminate the corrosion issue and looks to be more flexible than the usual stuff. Does seem to essentially be single sourced in the US.