Hello,
Yes GM has a windrestrictor. The part number is: 23353688. In 2017 the part was available with the code VLN when you were ordering the car. In 2018, this option is no longer available.
I have a 2019 Corvette Grand Sport on order and in a way to make sure that the part will be available when I am going to get the car in April I have ordered and received the part thru the GM parts department from my dealer. The book price is $1,150 CDN..I got it for just under $1,000. It is quite expensive for what it is but I talked to a guy that had it installed on his Corvette and he likes it very much (in fact his wife loves it).
It is a polycarbonate part. It is transparent and it has a small logo on it. It is approx 32 inches long by 5.25 inches wide and about 0.375 inch thick. It come with a template to show where you need to drill 4 holes and the hardware (4 bolts, flat washer, 2 metal fixtures and plastic bushing). It is fairly easy to instal. It can be removed by unscrewing the 4 bolts but the metal fixture will stay on the plastic cover behind the seats.
Pictures attached.
Alain
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