As some on the board knows I'm building this 64 Dart post car. It will have a hot 273/4 speed with 4:30 gears. I was over at the shop where the engine is being done and lo and behold while looking at the short block I noticed that the casting number is 5-13-66. My buddy has a book that has all of the old calenders and sure enough the block was cast Friday the 13th of May, 1966. I always wondered about this particular block in that the date is the only stamping on the block. How weird can that be!!!!!