Hello and welcome to the forum!!
Apologies for the delay in answering!
From the Engine Casting Number you've posted, 3970010, we have; 1969-1979, 302/350 cid, car & Truck, 2 & 4-Bolt, 4 bolt most common.
This is a pretty common block, used in a lot of vehicles.
A whole lot of these engines were made, each year, for 11 years!
This number from the passenger side of the block, VC6324F, is tough to decode!
It's apparently an pre-1971 code.
This is an Engine Assembly Code.
Each assembly plant keep a manual log of these codes until 1971, when the Government passed a law requiring all car manufacturers to systemically follow a sequence code and record them for each vehicle.
The law was actually passed in late 1969, the car companies were notifed in early 1970, the law would be in effect for the 1971 model year and from then on.
Chevrolet standardized these codes sometime in early 1970 in all assembly plants and began confirming to the new law.
The engine codes before 1971 were somewhat random, from plant to plant and their meaning is well cloaked in the history.
So, with this info, we can safely assume this may well be the original engine in your Impala.
The Engine Casting Number fits and the pre-1971 Engine Assembly Code fits.
So, you can safely assume this is a 1969, 350.
Hope some of this helps!
Don't be a stranger on the forum!
Stop by from time to time and let us know how it's going with your Impala!
