My 53 has a 59 235 in it. There are three numbers on the block that give information. First, the
casting number is located on the front half of the passenger side, down near the oil dipstick. The casting number 3764476 is a 58-62 Chevy 6. The
casting date is on the rear half of the passenger side, (as Frank50 says) behind the top of the starter (can just barely see it with the starter in place). The casting date is D229 which corresponds to a casting date of April 22, 1959. Finally, the
assembly date is engraved (or stamped) on the flat boss behind the distributor. The assembly date number is F424A which breaks down to Flint, MI assembly plant, assembled on April 24, and is a type A. Type A was a 235 6 cylinder engine with standard transmission or overdrive and standard duty clutch. Used in passenger and delivery vehicles.
If all of my research and decoding is correct, they must have been churning out those trucks, the engine must have been still warm if they were assembling it two days after it was cast.
I think if you take off your starter and clean up the block behind it, you will see the casting date.
