GTS engine ID

Your block casting date will be on the side of the block.....

http://www.yearone.com/updatedsinglepages/Id_info/mopar/mopar casting numbers/images/tech1.jpg

You need the build date of the car as well. In 1967, if the block casting date is within 3 months before the build date of the car, that is considered a "numbers-matching" block. '67-back, thats the only way to tell...its mostly a guess. '68-up they started the VIN/S.O. number stampings on the blocks/trans/rear end housing.