This is the correct size for your Buick Grand National or any other G-Body that had the DIN and a half stereo. Will also work in most GM vehicles in the '80s to '90s like the Fiero. Also Chrysler vehicles.
Comes with the wiring harness also so it is a direct plug in.
You can Google search the part number and it will tell you all the features. It is a top of the line model.
Price is firm. Thank you for looking and have a great day