Hello,
This is Winston the owner of the 87 Buick Grand National Convertible. Yes, I did live in St. Louis and now reside in Tampa, Florida. This car is very unique since it was originally a sunroof before being cut into a convertible in 1988. The original owner decided to make it into a convertible after seeing a white 87 white T-type convertible that was made by Coachbuilders. The dealership charged the original owner 10K to have the car made into a power-top convertible on a seperate invoice. The body was taken off the frame and reinforced in the floor in the trunk and in various places.
Note: This is the same car that is seen in Kirbans book as a rare GN. Also, in the 1980's Coachbuilders only cut 1 T-type and 1 GN.