Yeah I think it was from a 57 not a 55. I did have the numbers somewhere? I know that the block feels much heavier then a bare 350. To my knowledge it came out of a 57 Belair and was taken out to install a bigger motor. When I bought the block it had been sitting under a tree with a tarp and rope on it for around 20 years. Complete from carb to pan and I could still turn it from the flywheel. Pretty good find for $75.