[Mart]

Thanks David. I think you might be assuming my car is RHD, but it's a LHD American spec car.
But applying the logic you describe, For my LHD car, both fuel line and wires for the tail lights ought to be run down the left frame rail.
Hopefully I have read that right and made the right assumption.

Thanks for the detailed reply. You really are the man for these type of questions.
Much appreciated.
Mart.