Where is the air ride copressor on a 77 coupe deville?

On a 1977 Cadillac Coupe DeVille, the air ride compressor is typically located in the trunk (boot), on the passenger side, near the back. It's often mounted to the inner wheel well or the body itself in that area. It might be somewhat hidden, so you might need a flashlight to locate it. It's usually a fairly sizable cylindrical unit with a number of lines and electrical connections attached.