CE blocks were only made as short-blocks or as "fitted blocks" (just block and pistons). That complete XCD engine assembly may have been built up at Flint using a finished CE short-block intended for an LT-1 replacement as its foundation. Note that the "CE" stamp is on the outboard end of the pad (where they're always found), and the production code stamp is on the inboard end of the pad, in its normal location.
I've only seen one other pad with both the "CE" stamp and the production stamping, and several of us came to that conclusion on that one too.
