GM A Body styles 1970-72

[Canuck]

I am trying to get a handle on GM A body styles from 1970-72 and understand why GM offered some marques in 2 dr hardtop and 2 dr coupe (post) in some years but not all.

I am Familiar with the Olds Cutlass and 442, which offered a two door post all three years but the 442 was not available on a post coupe in 71. I cant find any reference to a Chevelle 2 dt post after 69 yet Buick and Pontiac came and went with 2 dr post offerings in the 3 year span. Anyone know why the Chevelle was never offered as a 2 dr post or are they so rare you just dont see them?