nowadays people are all about AC. When I was younger I hated popping the hood and seeing AC. 68 is a one year deal, I can imagine that pad is hard to find.
I got really lucky and found my 1968 A/C vent box with perfect chrome vents that could easily pass for NOS ones. It came with a really nice black lower trim piece too. All I did was an Internet search and it came up on some weird Buy and Sell website in Colorado.
The seller told me it was sitting is his shop for 30 years. He also shipped it before I paid for it, and said if I didn't like it, I didn't have to pay!