I'll take a stab at it from memory....
The Gran Coupe was an upscale model in the Barracuda line, engine choices were 225, 318, 383-2V and 383-4V.
They came with Gran Coupe badging on the front fenders, tail panel and inside door panels. Interiors were fancy, leather or cloth inserts in the front seats, cloth also in the rear seat when so equipped.
Overhead consolette with accessory guages and some extra mouldings on the exterior.
I think I am forgetting something.........
Barry