How to match

The PO did a linex coat on entire inside of tube but neglected to pull out a box on the hump over the transmition right were it goes up to the firewall. Is there a small kit that I could roll on or spray that would match

You could try the Raptor liner or similar but you won't get a texture match. You'll probably have a hard time getting the black to match as well. I would go back to LineX and have them patch it in if your worried about an exact or very close match.