This is a 1966 396 motor, casting 3855961, it is a 4 bolt block, date code is E-19-6, it is 30 over with no ridge at the top of cyc, the pad looks like some machine shop stamped some numbers on it. On the bottom of the block back by the oil filter it has T0506 stamped on it, which looks like factory stamping. It has the steel crank with stock rods. It looks like the small dome pistons, about 10 1/4. not the 11 to 1. I have a set of 858 square port heads that are dated late 65 that would have came on a 66 motor also. Selling short block foe 1800. Call 352-216-2273