Welcome to the world of partially-informative replies.
The number you posted is the partial VIN. It's the last 8 digits of the original host vehicle's VIN. The first digit indicated the year, the second indicated the plant the vehicle was manufactured at and the last 6 was the production sequence. Having a decent eye for poorly stamped Mopar numbers, that one might start with 3B, which would be a '73 engine installed into a vehicle produced at Dodge main.
However, there are other things that nail down the date. Look down behind the ignition coil from the top with a bright light. There's a pad on the block facing upward that contains more info. Once you scrape it off, you'll see a string of characters that resemble H225R 3018 1644. Your's will not be exactly the same but that's the format.
H225R...The letter is the year code. H would be 1973, G 1972 and so forth. 225 is the displacement, R is for regular fuel. The two pairs of 4 digits afterward are, in order, the 10,000 day calendar assembly date and then engine number produced that day. You can enter the 4 digit date code into an online decoder. They "might" be reversed between the pairs of numbers. There are no dates cast into the block on a Slant, that's V8 only. The 4-digit numbers cast there are not date codes. Last, it looks like the engine is wearing original Chrysler blue, so that's '70 up. Good luck.
EDIT: I just noticed cylinder head. That's a '75 and later head at least, so who knows until you find all the numbers.