[iluv69s]

the 052 cast number means it was of the original design as opposed to a later GM block..there were many alum blocks made beside the original 'original' 69 that came in the cars...A few clues to look for. Does the block have screw-in freeze plugs..or press-in? Is there a small stamped 2 or digit number on the rear of the block in the center above the bell housing mounting flange..same number would be stamped on the main caps...a date code and small cast number may be located down on the side of the block near the motor mount area. Some of the known original ZL-1 blocks have the VIN stamped on the front pad and others have the VIN stamped down along side the oil filter. If it is one of the real blocks, you may have a small fortune there. Regardless, it is an awesome street motor!!! A few more pics may help. Good Luck.