Those are pics of Charles Goin (Goin Manta) former GT. That GT was destined fo a museum, till Charles bought it. As for the vinyl top, that was just an "Americanizing" thing that was done here in the US, not at the factory. My $.02 worth? I hate it! The vinyl top, I mean
Buick down here in Texas did Bastardize some opels with a vinyl top package for trim, along with a bumble-bee strip in the rear and the ugly rubber door guards that ran all the way between the wheel wells.
The "Vandergriff" special top only covered the back half of the roof from the rear door line down to the bottom of the rear window.
Fortunately I have seen that specific trim package where the customer opt'd not to have the roof done. Most of these were on blue cars with white vinyl and a white stripe.
I would however like to find a bumble bee stripe (GT/J)