I acquired a 4dr 65 Impala and not sure which big block I have. I looked in the locations recommended online and can’t locate numbers. I’m pretty sure it’s not original motor since it’s not an SS. There are some emblems in the glovebox with 396 on them, but just didn’t want to assume.

 

Hello there. Here is what I found for where to find the engine VIN: "The Engine VIN is a stamped code located at the front passenger side of the block, on the machined boss just below the Head." This is the web page containing this statement along with more detailed information on how to decipher the numbers which include abbreviated designation of the year of manufacture:

https://wowmusclecars.com/chevrolet-...ck-casting-no/

The web site is called Wow Muscle Cars. There are other sources if you use the Boolean search terms in Google: "finding numbers on chevy big block engine". Do not use quotation marks or it will only search for that exact phrase. You will find a large number of Youtube videos as well as reference web sites on engine identification, many which specialize in GM engines or GM big blocks.

You can also buy one of the reference books that discuss building a high performance Chevy big block, as most or all of them contain reference information about identifying your block and your heads.