Blue Thunder
To the best of my recollection one helicopter was purchased from Briles Wing and Helicopter and they were also responsible for the modifications.
The Bell 206 N200 which was distroyed in the movie spent a lot of its time flying baggage between Oakland and San Francisco as a backup helicopter for SFO Helicopter Airlines. Hope this helps.
I also meant to add that Briles operate out of the Van Nuys Airport in southern California.