This article about the 8th "missing" TA convert has some information about the blue tops.
"Solving the Mystery of the “Lost” Eighth 1969 Pontiac Trans Am Convertible" - Motor Trend May 31, 2018
"There were a few pieces of the original top material left on the convertible frame, and both the material and the frame were blue, which was absolutely original to the car. But the undersides of the aftermarket tops that were available were black. Rick asked a large convertible top manufacturer in the Northeast if it could match the original material. The company agreed, but to do so it would have to purchase and custom-dye enough yardage for approximately 25 to 35 convertible tops. Rick reluctantly agreed, so his car would be authentic. And now all the other blue-top Trans Am convertibles will have the correct tops, as he contacted all the owners and supplied tops to them. He has a few spares, too, just in case."
