Usually on the top of the motor where the bell housing bolts up. Most of the time the numbers (7 or so) areplainly visible on a clean motor. Close investigation on the passenger's side will usually reveal a build date that is written in an alphanumeric code. The letters are much smaller and there is no real continuity between factories except the last number is always the last year in the production year. For instance a 3 means a year the ended in 3. But '63 or '73 ??? that takes some detective work. And the 'letter' in the code always corresponds to the month, IE, A is January, B is February, since E is the fifth letter, that would be the fifth month May.
Under the rocker cover.
chevy 350
That should be a 4 bolt main 350
A 350 with four bolt main caps is known as the "double-oh ten block." The last four numbers on the casting are 0010.
casting numbers are on the back of the block. there are numbers on the pad by the head on passenger side front that will reveal information too
look on the bellhousing on the driver's side and write the numbers down and look the numbers up. Google 350 Chevy casting numbers online or go to your local library. the year and the casting number will give you all the specs on that engine.
Pull the torque convertor out, they are on the front of the tranny inside the bell housing.
On the drivers side of the engine in back of the cylinder head there are casting numbers and next to the casting numbers are raised letters either 5.7 or 5.0.
350
The block casting numbers are on the top driver side of the bellhousing flange at the back of the engine. The engine code is stamped into a pad on the block deck in front of the passenger side cylinder head.
The back of the block will have a series of letters and numbers cast into it. That is what determines the date.
Find a book on casting numbers for chevys it will give you the year of the block the heads & the manifolds.