My A66 SPD 9/28/69 has X (2531894 D) heads cast 8-11-69 & 8-22-69 the # block is cast 7/8/69. The V-8 emblems have been on the flat hood cars and the early sport hood cars I have seen and seemed to come and go on the later after 11/69 sport hood equipped cars with 340 emblem.