Help with '77 engine block number

[biff]

I'm new to the site and I'm looking for a little help. My 77's VIN is 1Z37L7S4XXXX. While checking the engine block, I found the code: V0305CKZ. I know that the CKZ is for a 180hp MT car (so far so good). Does anyone know the meaning of the "V0305?"
Also, there is a smaller code on the block that I cannot make out, although the last five digits are the same as the last five digits of my VIN. Basically, I would like to know if the engine is the original. Any help or places to research would be helpful. Thanks in advance!

[DDLS1]

biff,

If the last 5 digits on your block match the last 5 on the vin tag she's an original!

[chuck]

biff, V=Flint Mich. plant 03=March 05= 5th day.Engine built in Flint on March 05. Chuck

[biff]

Thanks to all. I really appreciate your help. This is a lot faster than researching on my own. Chuck, where did you find the info on the engine block code?

[chuck]

Biff,I found that info in the 75 to 77 NCRS Judging Manual. Chuck