After I first saw Diamond Lil, with her top turret cut-out aft of the bomb bay, I searched the Internet for pictures of a B-24 or LB-30 with its top turret actually installed aft of the bomb, without any luck.

Not too long later, however, I picked up a copy of Steve Birdsall's Log of the Liberators (which is apparently out of print), which had just such a picture. According to the caption, this plane is a British LB-30 which flew with both the RAF's 159 Squadron and the 160 Squadron.

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From p. 7 of Log of the Liberators
Scan by heroicrelics.