340 with no stamped numbers on it

I have a 69 340 with no numbers stamped in the block. why. is this a warranty block or something. on one side it has the date code of 3-16-69. the other side it has 2780930-340-8 on the left side. I cannot find a number on the pad above the pan. I have a guy wanting to trade me some stuff for it and I would like to let him know what it is. It is a rotating short block. Thanks,Bill