What models of the Impala were made in 1972/ What model do I have?

How many different types of Impala's were produced in 1972? Any idea what they were?

The reason I ask is because I'm trying to figure out exactly what model a 1972 Impala is. I believe it is a Custom Coupe, but Im not sure. No matter how much I look online, I cant find a photo like it and I've never seen one personally. The most noticeable difference is the roof and rear windows. Unlike most 1972 Impalas, the rear windows come to a tier (or a closer point)... they are more triangular then rectangular. The rear window is bowed out, instead of con-caved in and the roof line is a little lower. Any idea what model this might be?