67 rear valance cut out question

Umm, if it is a true 383 car it should have dual cut-outs. If not it may be cloned or it has been replaced. As for changing it, that piece is the entire rear body panel. I just got one from 521 resto's and it is a nice piece. What I heard is they only made them with no backup light holes so those will need to be cut out. Mine has no holes which was perfect for my 68 383 Formula "S" auto on the floor. If yours is a true 383 car the 5th letter in the V.I.N. number should be an "H"..

Here is mine with the correct tips,