1968 Dash Trim question

[Corey Bowcutt]

I finally have all original dash trim pieces and am about to install them.  I ended up with a few of each of the pieces so am trying to decide which to use.  In the picture you can see the two right side trim pieces I have.  I have two questions.  1) One piece is chrome on the back and the other is not.  Is one more assembly line correct than the other?  2) I see a rectangular shadow line on both pieces.  What is the cause of this rectangular marking?

[Coralsnake]

There should be a small piece of foam glued to the back to prevent a rattle

[Corey Bowcutt]

Thank you Pete.  How about chrome vs. no chrome on back?

[Coralsnake]

Likely, Just a variance of manufacturing

[TLea]

 Gray on the backside just means it's a service piece

[Corey Bowcutt]

Thank you Tim.  The chrome one is in better condition so that is the one I was planning on using so it is great that that is an assembly line item