Splitting hairs is fun!
Yes, information was shared.....
A now defunct company called PAS built the GN/turbo T-Type, '89 turbo Trans-Am, and the Sy/Ty's (a few other cars too... )..... they took the freshly painted driveable vehicles right from GM and put the fancy schmancy interiors and exterior goodies on them and then shipped them to the dealers. Some believe that the exterior graphics (stickers) were put on at the dealer... some don't think so. There's a lot of speculation.
The information sharing process must have been really bad... ... the '89 turbo Trans-Am was an improvement drivetrain wise over the GN/turbo T-Type (better cylinder heads), but the Sy/Ty's are a complete headache when it comes to making them run right (stock vs. stock). Distributorless ignition from the GN would have solved at least 50% of the Sy/Ty problems... . poor cylinder heads, a weak bottom end, etc. , are some other problems.
Matt