Thanks guys! Great info!

So I have a customer that swears his car had a 71-4 B body style pass side splash. I painted the hole and the long angled slot on this picture of a 73 Cuda. You can see the hole and slot were never punched out. Like it was perf cut so it could be removed if needed. I think these may be rare examples of "use whatever is available to get the cars down the line".

The ones shown above with the hole and short parallel slit are the ones I know as 71-4 E body pass side splash. BUT whats the deal with the brake like wrapping around the frame? Wouldn't need a hole and slot in the splash. Right? What year did the brake line wrap under the frame?