Yup,
Pretty sure the 150 Business Coupe had fixed rear glass as well. The car I have now had a custom tan/white interior refit when it was restored in 2017. While it was decent, I wanted the B&W version of the DelRay interior to update the car with once it was repainted in B&W. Headliner is now done, armrests are changed into B&W (penguin style), and the seats are now recovered and ready to go in with the door panels once I finish the wiring. Here's what it did look like, and the way it will soon look.
The way it looked when I bought the car...
The way I want it to look except I'll have a candy cane shifter and belair trim on the dash.
The pictures that inspired the change to black and white. I copied the 2 tone handles seen here but haven't decided on belts and buckles yet. I'll likely run deluxe GM like the Camaro's used.