The first two have the same back cover but different coloured inner covers - one blue, one black. The third and fourth have a reset back cover and the same two colours but the pattern on the inner cover in inverted. The original art still exists - in Palmer's archives at Concordia University.
Palmer was a newspaperman for many years in Montreal and one of his buddies put a couple of free plugs in his column.
The first was “[d]on’t expect to see Al Palmer around these parts for a long time to come. His new book, Montreal Confidential, hit the news stands yesterday. It tells a lot of stories about what made the wheels click in this town in Al’s day, and it names names.” (“Fitz”, “On And Off The Record”, Montreal Gazette, September 21, 1950 p. 11). A few weeks later an update, “Al Palmer’s Montreal Confidential the fastest selling two-bitter ever to hit Montreal news-stands. Predictions are 25,000 copies plus locally, a record. Sales in the hinterland also good.” (“Fitz”, “On And Off The Record”, Montreal Gazette, October 3, 1950 p. 18.)
Variant 1 back cover
Variant 2 back cover